A synchronous monitoring system for soil greenhouse gas and nitrogen oxide fluxes

Abstract

The invention discloses a soil greenhouse gas and nitrogen oxide flux synchronous monitoring system, belonging to the field of gas monitoring technology. The soil greenhouse gas and nitrogen oxide synchronous monitoring system comprises a plurality of soil respiration chambers, a control system, a nitrogen oxide analyzer, a gas chromatograph and a data recording system, wherein the soil respiration chamber is connected to the control system, the data recording system is respectively connected to the nitrogen oxide analyzer and the gas chromatograph for recording monitoring data, and further comprises a valve box; the control system is connected to the valve box, and the valve box has a first outlet, a second outlet and an air inlet, the first outlet is connected to the nitrogen oxide analyzer, the second outlet is connected to the gas chromatograph, the nitrogen oxide analyzer is connected to the air inlet, and the air inlet is used to supplement air; the invention arranges a valve box in the monitoring system, so that the determination of the gas chromatograph can match the closing time of the respiration chamber, so as to achieve the purpose of real-time synchronous monitoring.

Description

Technical Field

[0001] The present invention relates to the technical field of gas monitoring, and more specifically to a soil greenhouse gas and nitrogen oxide flux synchronous monitoring system. Background Art

[0002] Greenhouse gases refer to some gases in the atmosphere that can absorb long-wave radiation reflected by the ground and re-emit radiation. Their function is to make the earth's surface warmer, similar to the role of a greenhouse in intercepting solar radiation and heating the air inside the greenhouse. This effect of greenhouse gases making the earth warmer is called the "greenhouse effect." Water vapor, carbon dioxide, nitrous oxide, freon, methane, etc. are the main greenhouse gases in the earth's atmosphere. In addition, nitrogen oxides are an air pollutant, a compound composed of two elements, nitrogen and oxygen. Nitrogen oxides are the general term for NO and NO2, with NO being used instead. x Indicates. NO x It is a key precursor of inhalable atmospheric aerosol particles, NO x It is also the precursor of O3, an important pollutant in the near-ground atmosphere. x The end product of photochemistry is HNO3. The deposition of excessive HNO3 will lead to eutrophication of surface water and acidification and poisoning of land, wetland and groundwater systems, thereby causing damage to terrestrial and aquatic ecosystems, and ultimately have adverse effects on human health and ecological environmental safety.

[0003] Soil is the main source of these gases. x The emission can be monitored by laser-type instruments, and the gas extracted from the respiration chamber is fed to the laser analyzer for synchronous observation. However, the testing cost of laser-type instruments is high and there are instability issues. Gas chromatograph is an instrument that uses chromatographic separation technology and detection technology to perform qualitative and quantitative analysis on complex mixtures of multiple components. Compared with laser-type instruments, gas chromatographs are less expensive, and the measurement technology of gas chromatographs is more stable and mature. Therefore, it can be used for joint analysis with the respiration chamber to achieve real-time continuous monitoring of N2O, CH4 and CO2 in the soil; NO x When monitoring, compared with laser-type nitrogen oxide analyzers, chemiluminescence-based nitrogen oxide analyzers are low-cost and can meet detection needs to accurately measure NO x purpose.

[0004] CO2, CH4 and N2O are the main components of greenhouse gas monitoring at present. x It is atmospheric PM 2.5 In order to simultaneously xTo monitor CO2, CH4 and N2O, a breathing chamber, control system, nitrogen oxide analyzer and gas chromatograph are required. During the monitoring process, the nitrogen oxide analyzer can perform real-time monitoring and match the closing time of the breathing chamber. However, the gas chromatograph uses its own analysis software to establish batch processing to achieve continuous measurement of samples, but it does not match the closing time of the breathing chamber and cannot perform real-time monitoring. Summary of the invention

[0005] In view of the above problems, the present invention provides a soil greenhouse gas and nitrogen oxide flux synchronous monitoring system, in which a valve box is arranged so that the measurement of the gas chromatograph can be matched with the closing time of the soil respiration chamber, thereby achieving the purpose of real-time synchronous monitoring.

[0006] The object of the present invention is to provide a soil greenhouse gas and nitrogen oxide flux synchronous monitoring system, comprising a plurality of soil respiration chambers, a control system, a nitrogen oxide analyzer, a gas chromatograph and a data recording system, wherein the soil respiration chamber is connected to the control system, the data recording system is respectively connected to the nitrogen oxide analyzer and the gas chromatograph for recording monitoring data, and also includes a valve box.

[0007] The control system is communicated with the valve box, and the valve box has a first outlet, a second outlet and an air inlet, the first outlet is connected to the nitrogen oxide analyzer, the second outlet is connected to the gas chromatograph, and the nitrogen oxide analyzer is connected to the air inlet, and the air inlet is used to replenish air.

[0008] The valve box and the first outlet are opened, and the gas enters the nitrogen oxide analyzer through the first outlet. The nitrogen oxide analyzer is used to analyze the gas at the first outlet. After the gas analysis at the first outlet is completed, the first outlet is closed, and the second outlet is opened. The gas enters the gas chromatograph through the second outlet until the gas concentration at the second outlet meets the gas chromatography analysis. The second outlet is then closed. While the gas chromatograph is analyzing the gas at the second outlet, the first outlet is opened, and the cycle of monitoring nitrogen oxides and greenhouse gases is repeated.

[0009] In a preferred embodiment of the present invention, the first outlet is opened, the second outlet and the air inlet are closed, the control system controls the soil respiration chamber to be closed, and the gas is extracted for nitrogen oxide analysis. It can be understood that the nitrogen oxide analysis is real-time monitoring.

[0010] In a preferred embodiment of the present invention, after the nitrogen oxide analysis is completed, the control system controls the soil respiration chamber to open and evacuate the gas in the pipeline and the soil respiration chamber.

[0011] In a preferred embodiment of the present invention, after the emptying is completed, the first outlet is closed, and the air inlet is opened. The air inlet is used to supplement the nitrogen oxide analyzer with air. When the gas chromatograph is taken out of the gas, the control system controls the soil respiration chamber to be closed, and the second outlet is opened. The gas is extracted as the background and as the initial gas extraction. After the gas extraction is completed, the second outlet is closed, and a gas chromatography analysis is performed on the extracted gas.

[0012] The second outlet is opened to extract the gas in the suction chamber as secondary gas extraction. After the gas extraction is completed, the second outlet is closed to perform secondary gas chromatography analysis on the extracted gas.

[0013] The second outlet is opened to extract the gas in the soil respiration chamber as three gas extractions. After the gas extraction is completed, the second outlet is closed and the extracted gas is subjected to three gas chromatography analyses.

[0014] Specifically, during the initial gas extraction, the secondary gas extraction and the tertiary gas extraction, the switching of the valve box is regulated by using the time sequence in the method file set in the gas chromatograph.

[0015] In a preferred embodiment of the present invention, when performing three gas chromatography analyses, the first outlet is opened and the air inlet is closed at the same time, and the gas in the pipeline and the soil respiration chamber is emptied. After the evacuation is completed, the control system switches to the next soil respiration chamber for measurement. Specifically, during the three gas chromatography analyses, it indicates that the analysis and sampling of one soil respiration chamber is completed. At the same time as the three gas chromatography analyses, the gas in the pipeline and the soil respiration chamber is emptied to prepare for the measurement of the next soil respiration chamber.

[0016] In a preferred embodiment of the present invention, during emptying, the control system controls the soil respiration chamber to open, and the gas in the pipeline and the soil respiration chamber is emptied through the pump of the nitrogen oxide analyzer, and the emptying time is 5 minutes.

[0017] In a preferred embodiment of the present invention, the valve box comprises: a fixed frame, and a first solenoid valve, a second solenoid valve, a third solenoid valve and a sample air inlet fixedly connected to the fixed frame.

[0018] The sample air inlet is connected to the control system.

[0019] One end of the first solenoid valve is connected to the sample gas inlet through a first valve box gas pipeline, and the other end of the first solenoid valve is connected to the nitrogen oxide analyzer through the first outlet.

[0020] One end of the second solenoid valve is connected to the sample gas inlet through a second valve box gas pipeline; the other end of the second solenoid valve is connected to the gas chromatograph through the second outlet.

[0021] The third solenoid valve is communicated with the air inlet through a third valve box gas pipeline.

[0022] It can be understood that the first valve box gas pipeline and the second valve box gas pipeline are both branch pipelines, and the gas is distributed to the first valve box gas pipeline or the second valve box gas pipeline through the main pipeline connected to the control system. The time sequence in the method file set in the gas chromatograph is used to control the switching of the first solenoid valve, the second solenoid valve and the third solenoid valve.

[0023] In a preferred embodiment of the present invention, when analyzing nitrogen oxides, the sample gas enters from the sample gas inlet, passes through the first valve box gas pipeline, the first solenoid valve and the first outlet in sequence, and is sent to the nitrogen oxide analyzer for analysis.

[0024] When analyzing greenhouse gases, the sample gas enters from the sample gas inlet, passes through the second valve box gas pipeline, the second solenoid valve and the second outlet in sequence, and is sent to the gas chromatograph for analysis.

[0025] When air is replenished to the nitrogen oxide analyzer, the nitrogen oxide analyzer is replenished in sequence through the air inlet, the third solenoid valve, and the third valve box gas pipeline.

[0026] In a preferred embodiment of the present invention, the control system is an MCC-1-8 eight-channel control system. The control system can be connected to eight soil respiration chambers for use. After the test of one soil respiration chamber is completed, the control system is switched to another soil respiration chamber for monitoring.

[0027] Compared with the prior art, it has the following beneficial effects:

[0028] When monitoring greenhouse gases and nitrogen oxides, the present invention sets a valve box, and uses the solenoid valve in the valve box to control whether the sample gas is distributed to the nitrogen oxide analyzer or the gas chromatograph. The setting of the valve box can be used to regulate the batch processing of the gas chromatograph and match the opening and closing time of the soil respiration chamber.

[0029] The present invention is easy to operate and low in cost, and can realize real-time synchronous monitoring of greenhouse gases and nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the connection of the monitoring system of the present invention.

[0031] Figure 2 It is a schematic diagram of the time series during monitoring in the present invention.

[0032] Figure 3 It is a structural schematic diagram of the valve box in the present invention.

[0033] Figure 4 FIG. 5 is a path diagram of gas in the valve box. FIG.

[0034] Figure markings: 1-valve box, 11-fixed frame, 12-first solenoid valve, 121-first valve box gas pipeline, 122-first outlet, 13-second solenoid valve, 131-second valve box gas pipeline, 132-second outlet, 14-third solenoid valve, 141-third valve box gas pipeline, 142-air inlet, 15-sample air inlet. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] A soil greenhouse gas and nitrogen oxide flux synchronous monitoring system comprises a soil respiration chamber, a control system, a valve box 1, a nitrogen oxide analyzer, a gas chromatograph and a data recording system; Figure 1 shown.

[0037] The soil respiration chamber is connected to the control system, and the data recording system is connected to the nitrogen oxide analyzer and the gas chromatograph respectively to record monitoring data. The control system is connected to the valve box 1, and the valve box 1 has a first outlet 122, a second outlet 132 and an air inlet 142. The first outlet 122 is connected to the nitrogen oxide analyzer, and the second outlet 132 is connected to the gas chromatograph. The nitrogen oxide analyzer is connected to the air inlet 142, and the air inlet 142 is used to replenish air.

[0038] The valve box 1 and the first outlet 122 are opened, and the gas enters the nitrogen oxide analyzer through the first outlet 122. The nitrogen oxide analyzer is used to analyze the gas at the first outlet 122. After the gas analysis of the first outlet 122 is completed, the first outlet 122 is closed, and the second outlet 132 is opened. The gas enters the gas chromatograph through the second outlet 132 until the gas concentration of the second outlet 132 meets the gas chromatography analysis, and then the second outlet 132 is closed. While the gas chromatograph is analyzing the gas at the second outlet 132, the first outlet 122 is opened, and the cycle of monitoring nitrogen oxides and greenhouse gases is repeated.

[0039] It should be noted that the control system is used to control the closure of the soil respiration chamber and the switching between different soil respiration chambers. For example, there are eight soil respiration chambers, each of which has a first air outlet, and each of the first air outlets is connected to the control system. The control system has eight air inlets and one second air outlet, and the second air outlet is connected to the gas inlet. The gas of the soil respiration chamber that is switched to enters the control system, and then is sent to the valve box 1 through the second air outlet on the control system, and is distributed to different analytical instruments by the valve box 1.

[0040] The first outlet 122 is used for feeding samples to the nitrogen oxide analyzer for analysis, the second outlet 132 is used for transporting samples to the gas chromatograph for gas chromatography analysis, and the air inlet 142 is used to supplement air to the nitrogen oxide analyzer. The air is supplemented because when the sample is switched to the gas chromatograph, the nitrogen oxide is equivalent to having no air intake because it is always in the pumping stage. If no gas enters, it will affect the service life of the instrument, so air is supplemented through the air inlet 142.

[0041] The switching of the solenoid valve in the valve box 1 is controlled by the time sequence in the method file set on the gas chromatograph, such as Figure 2 The analysis steps are shown below.

[0042] Phase 1: Open the first outlet 122, close the second outlet 132 and the air inlet 142, the control system controls the soil respiration chamber to close, and extract samples for nitrogen oxide analysis.

[0043] After the nitrogen oxide analysis is completed, the control system controls the breathing chamber to open, and the gas in the pipeline and the soil breathing chamber is emptied through the pump of the nitrogen oxide analyzer.

[0044] Specifically, the test starts with nitrogen oxide analysis. First, in the time sequence of the first method file in the gas chromatography, the first outlet 122 is opened, and the second outlet 132 and the air inlet 142 are closed. At this time, the control system controls the soil respiration chamber to be in a closed state, and the extracted gas is used for analysis by the nitrogen oxide analyzer. The analysis time is 6 minutes. After 6 minutes, the control system controls the soil respiration chamber to open, but the solenoid valves connected to the three outlets remain unchanged. The pump of the nitrogen oxide analyzer is used to empty the entire pipeline and the soil respiration chamber for 5 minutes. That is, in the sequence of the first method file in the gas chromatography, the time is 11 minutes.

[0045] Next, the first outlet 122 is closed, and the air inlet 142 is opened to supply air to the nitrogen oxide analyzer. The second stage, the third stage, and the fourth stage are used for gas extraction analysis of gas chromatography.

[0046] The second stage: the first outlet 122 is closed, the air inlet 142 is opened, and the air is supplemented to the nitrogen oxide analyzer by the air inlet 142. When the gas chromatograph is taken out of the gas, the soil respiration chamber is closed, the second outlet 132 is opened, and the gas in the soil respiration chamber is extracted as the background and as the initial gas extraction. After the gas extraction is completed, the second outlet 132 is closed, and the extracted gas is subjected to gas chromatography analysis;

[0047] Specifically, when the second method file in the gas chromatography is running, the control system controls the soil respiration chamber to be closed, and the second outlet 132 is opened to extract the gas just covered by the soil respiration chamber as the background, that is, Figure 2 The gas extraction at S1 at the 0th minute takes 0.4 minutes, and the length of the pipeline used for gas extraction is 10 meters. After 0.4 minutes, the second outlet 132 is closed. At this time, the gas in the soil respiration chamber is in an accumulation state. After 0.4 minutes, the gas chromatography analyzes the concentrations of CH4, CO2 and N2O. The analysis time is 9.6 minutes. Therefore, the time series of the second method file is Figure 2 10min at S2.

[0048] The third stage: opening the second outlet 132, extracting the gas in the soil respiration chamber as secondary gas extraction, and after the gas extraction is completed, closing the second outlet 132, and performing gas chromatography analysis on the extracted gas; the third method file in the gas chromatography method has the same time series setting as the second method file, and is used to extract the gas accumulated in the soil respiration chamber for 10 minutes.

[0049] The fourth stage: open the second outlet 132, extract the gas in the soil respiration chamber as the third gas extraction, after the gas extraction is completed, close the second outlet 132, and perform gas chromatography analysis on the extracted gas; at the same time, open the first outlet 122, close the air outlet, and empty the gas in the pipeline and the soil respiration chamber through the pump of the nitrogen oxide analyzer. After the emptying is completed, the control system switches to the second soil respiration chamber for measurement.

[0050] When the fourth method file in the gas chromatography method is run, the gas accumulated in the soil respiration chamber for 20 minutes is extracted, that is, Figure 2 At S3. After the extraction is completed, the second outlet 132 is closed, and the gas chromatograph analyzes the gas taken three times. However, at this time, the first outlet 122 is opened, the air inlet 142 is closed, and the soil respiration chamber and the pipeline are emptied using the pump of the nitrogen oxide analyzer, and the emptying time is also 5 minutes. After the emptying is completed, the control system switches to the second soil respiration chamber and starts the measurement of the next soil respiration chamber. It takes a total of 11 minutes to empty the nitrogen oxide analyzer and the pipeline. Therefore, the total duration of the time series in the gas chromatography method is 16.4 minutes, specifically including 0.4 minutes for air extraction at the 0th minute, 5 minutes for emptying after three air extractions, and 11 minutes for emptying when starting the next soil respiration chamber measurement. Then the second method file-the fourth method file used in the second stage-the fourth stage is cycled again, and so on, and the above operations are repeated to complete the analysis of other soil respiration chambers.

[0051] The valve box 1 is disposed between the control system, the nitrogen oxide analyzer, and the gas chromatograph. The valve box 1 is used to control the opening and closing of the first outlet 122 , the second outlet 132 , and the air inlet 142 .

[0052] like Figure 3-Figure 4 As shown, the valve box 1 includes a fixing frame 11, a first solenoid valve 12, a second solenoid valve 13, a third solenoid valve 14 and a sample air inlet 15. The first solenoid valve 12, the second solenoid valve 13, the third solenoid valve 14 and the sample air inlet 15 are all fixedly connected to the fixing frame 11. One end of the first solenoid valve 12 is connected to the sample air inlet 15 through a first valve box gas pipeline 121, and the other end of the first solenoid valve 12 is connected to the nitrogen oxide analyzer through the first outlet 122; one end of the second solenoid valve 13 is connected to the sample air inlet 15 through a second valve box gas pipeline 131; the other end of the second solenoid valve 13 is connected to the gas chromatograph through the second outlet 132; the third solenoid valve 14 is connected to the air inlet 142 through the third valve box gas pipeline 141. Air is replenished through the air inlet 142.

[0053] Figure 4 The figure is a path diagram of the gas in the valve box 1. It should be noted that the arrows indicate the flow direction of the gas. When analyzing nitrogen oxides, the sample gas enters from the sample air inlet 15, passes through the first valve box gas pipeline 121, the first solenoid valve 12 and the first outlet 122 in sequence, and is sent to the nitrogen oxide analyzer for analysis; when analyzing greenhouse gases, the sample gas enters from the sample air inlet 15, passes through the second valve box gas pipeline 131, the second solenoid valve 13 and the second outlet 132 in sequence, and is sent to the gas chromatograph for analysis. When replenishing the nitrogen oxide analyzer with air, the nitrogen oxide analyzer is replenished through the air inlet 142, the third solenoid valve 14 and the third valve box gas pipeline 141 in sequence.

[0054] The switch of each solenoid valve in the valve box 1 is controlled by a gas chromatography method file. Specifically, a batch process is set in a Shimadzu gas chromatography workstation.

[0055] The control system is an MCC-1-8 eight-channel control system purchased from Beijing Lijia United Technology Co., Ltd., model SF-3000.

[0056] Example 1

[0057] Each soil respiration chamber lasts 36 minutes from the start of measurement to the end, that is, 8 soil respiration chambers will obtain 40 flux data in one day, which means that each soil respiration chamber will perform 5 measurements per day.

[0058] (1) During the measurement process, each soil respiration chamber is closed twice, respectively for monitoring NO and N2O fluxes. For each soil respiration chamber, the first 6 minutes are used for real-time analysis of NO concentration; the gas sample is pumped into the nitrogen oxide analyzer at a flow rate of 1L / min, and the nitrogen oxide analyzer detects and records the NO concentration every 10 seconds. The 1 minute after the soil respiration chamber is closed is the equilibrium time. Due to the concentration fluctuations caused by the switching and closing of the soil respiration chamber, it is not used for the calculation of NO emission rate. The slope of the NO concentration change over time in the next 5 minutes is used to calculate the emission rate.

[0059] (2) After the NO concentration analysis is completed, the soil respiration chamber is opened and emptied for 5 minutes to remove the residual gas in the soil respiration chamber and the pipeline. During the evacuation, the pump of the nitrogen oxide analyzer is used to evacuate the residual gas in the soil respiration chamber and the pipeline.

[0060] (3) After the emptying, the same soil respiration chamber was closed again, and the gas path was switched to perform N2O concentration analysis. The N2O analysis lasted for 20 minutes, and sampling and analysis were performed at 0 minutes, 10 minutes and 20 minutes after closing. The N2O concentration accumulation of the three samples was used for N2O flux calculation. After the N2O analysis, the soil respiration chamber was opened and emptied for 5 minutes, and then the next soil respiration chamber was used for the same sampling and analysis. A pressure balance tube was installed on the top of each soil respiration chamber to maintain the pressure balance inside and outside the soil respiration chamber. The nitrogen oxide analyzer was zero-calibrated using high-purity nitrogen every week. The NO concentration in high-purity nitrogen was <0.02ppb. Multi-point calibration was performed monthly using a multi-gas calibrator, zero gas and standard gas. Since the soil respiration chamber is opaque, the photochemical decomposition of NO2 can be ignored. At the same time, the change in NO2 concentration within 6 minutes of the soil respiration chamber closing was analyzed, and it was found that the NO2 concentration remained almost unchanged, so the chemical reaction between NO and O3 can also be ignored.

[0061] It should be noted that the model of the multi-gas calibrator is 146 i-BT3BEA; the zero gas was purchased from Thermo Fisher Scientific Inc., Waltham, Massachusetts, USA, with the model number 111-B2R, and the standard gas was purchased from Dalian Top Gas Co., Ltd., Dalian, China, with a gas concentration of 50.0 ppm.

[0062] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0063] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A soil greenhouse gas and nitrogen oxide flux synchronous monitoring system, comprising a plurality of soil respiration chambers, a control system, a nitrogen oxide analyzer, a gas chromatograph and a data recording system, wherein the soil respiration chamber is connected to the control system, and the data recording system is connected to the nitrogen oxide analyzer and the gas chromatograph respectively for recording monitoring data, characterized in that: Also includes a valve box (1); The control system is in communication with the valve box (1); the valve box (1) is provided with a first outlet (122), a second outlet (132) and an air inlet (142); the first outlet (122) is connected to the nitrogen oxide analyzer; the second outlet (132) is connected to the gas chromatograph; the nitrogen oxide analyzer is connected to the air inlet (142); the air inlet (142) is used to supplement air; The valve box (1) and the first outlet (122) are opened, and the gas enters the nitrogen oxide analyzer through the first outlet (122). The nitrogen oxide analyzer is used to analyze the gas at the first outlet (122). After the gas analysis at the first outlet (122) is completed, the first outlet (122) is closed, and the second outlet (132) is opened. The gas enters the gas chromatograph through the second outlet (132) until the gas concentration at the second outlet (132) satisfies the gas chromatography analysis. Then, the second outlet (132) is closed. While the gas chromatograph is analyzing the gas at the second outlet (132), the first outlet (122) is opened, and the nitrogen oxide and greenhouse gas are monitored in a repeated cycle. The valve box (1) comprises: a fixed frame (11), and a first solenoid valve (12), a second solenoid valve (13), a third solenoid valve (14) and a sample air inlet (15) fixedly connected to the fixed frame (11); The sample air inlet (15) is connected to the control system; One end of the first solenoid valve (12) is connected to the sample gas inlet (15) through a first valve box gas pipeline (121), and the other end of the first solenoid valve (12) is connected to the nitrogen oxide analyzer through the first outlet (122); One end of the second solenoid valve (13) is connected to the sample gas inlet (15) through a second valve box gas pipeline (131); the other end of the second solenoid valve (13) is connected to the gas chromatograph through the second outlet (132); The third solenoid valve (14) is in communication with the air inlet (142) via a third valve box gas pipeline (141).

2. A soil greenhouse gas and nitrogen oxide flux synchronous monitoring system according to claim 1, characterized in that: The first outlet (122) is opened, the second outlet (132) and the air inlet (142) are closed, and the control system controls the soil respiration chamber to close and extract gas for nitrogen oxide analysis.

3. A soil greenhouse gas and nitrogen oxide flux synchronous monitoring system according to claim 2, characterized in that: After the nitrogen oxide analysis is completed, the control system controls the soil respiration chamber to open and exhaust the gas in the pipeline and the soil respiration chamber.

4. A soil greenhouse gas and nitrogen oxide flux synchronous monitoring system according to claim 3, characterized in that: After the emptying is completed, the first outlet (122) is closed, the air inlet (142) is opened, and the air inlet (142) is used to supplement the nitrogen oxide analyzer with air. When the gas chromatograph is taken out of the gas, the control system controls the soil respiration chamber to be closed, and the second outlet (132) is opened to extract gas as the background and as the initial gas extraction. After the gas extraction is completed, the second outlet (132) is closed, and a gas chromatography analysis is performed on the extracted gas; Opening the second outlet (132) to extract gas from the soil respiration chamber as secondary gas extraction, and after the gas extraction is completed, closing the second outlet (132) to perform secondary gas chromatography analysis on the extracted gas; The second outlet (132) is opened to extract the gas in the soil respiration chamber as three gas extractions. After the gas extraction is completed, the second outlet (132) is closed and the extracted gas is subjected to three gas chromatography analyses.

5. A soil greenhouse gas and nitrogen oxide flux synchronous monitoring system according to claim 4, characterized in that: When performing three gas chromatography analyses, the first outlet (122) is opened and the air inlet (142) is closed at the same time to exhaust the gas in the pipeline and the soil respiration chamber. After the exhaust is completed, the control system switches to the next soil respiration chamber for measurement.

6. A soil greenhouse gas and nitrogen oxide flux synchronous monitoring system according to claim 3 or 5, characterized in that: During emptying, the control system controls the soil respiration chamber to open, and the gas in the pipeline and the soil respiration chamber is emptied through the pump of the nitrogen oxide analyzer.

7. A soil greenhouse gas and nitrogen oxide flux synchronous monitoring system according to claim 1, characterized in that: When analyzing nitrogen oxides, the sample gas enters from the sample gas inlet (15), passes through the first valve box gas pipeline (121), the first solenoid valve (12) and the first outlet (122) in sequence, and is sent to the nitrogen oxide analyzer for analysis; When analyzing greenhouse gases, the sample gas enters from the sample gas inlet (15), passes through the second valve box gas pipeline (131), the second solenoid valve (13) and the second outlet (132) in sequence, and is sent to the gas chromatograph for analysis; When air is replenished to the nitrogen oxide analyzer, the nitrogen oxide analyzer is replenished in sequence through the air inlet (142), the third solenoid valve (14), and the third valve box gas pipeline (141).

8. The soil greenhouse gas and nitrogen oxide flux synchronous monitoring system according to claim 1, characterized in that: The control system is an MCC-1-8 eight-channel control system.

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