A fully automatic carbon dioxide flux measurement assimilation system

Abstract

The utility model discloses a kind of full-automatic carbon dioxide flux measurement assimilation system, belong to environmental monitoring and gas measurement technical field, comprising: multiple full-automatic opening and closing sampling box, for sealing to be measured area;A multi-port selector valve, its multiple gas inlets are connected with the gas outlet of the multiple sampling box respectively through gas path pipeline whose length does not exceed 5 meters, inner diameter is 4~6mm;A greenhouse gas analyzer, its gas inlet is connected with the common outlet of the multi-port selector valve through gas path pipeline.The utility model is integrated multiple full-automatic opening and closing sampling box and advanced greenhouse gas analyzer, the system can accurately measure carbon dioxide flux.System can automatically switch gas sampling point by multi-port selector valve, so that measurement process is more efficient and has higher accuracy.System uses high-precision sensor to ensure that the environmental data collected has high precision, which is crucial for the calculation of carbon dioxide flux.

Description

Technical Field

[0001] This utility model relates to the field of environmental monitoring and gas measurement technology, and more specifically, to a fully automatic carbon dioxide flux measurement and assimilation system. Background Technology

[0002] Carbon dioxide flux is a crucial indicator for measuring the carbon cycle in ecosystems and is widely used in fields such as ecology, climatology, environmental protection, and agricultural science. Accurate and real-time measurement of carbon dioxide flux is essential for understanding carbon absorption and release processes in ecosystems, and for developing and implementing effective emission reduction and environmental protection measures.

[0003] Among existing carbon dioxide flux measurement techniques, common methods include the airbag method, the closed-box method, and the eddy covariance method. The closed-box method, due to its relative simplicity and efficiency, is often used for small-scale ecosystem monitoring. This method involves completely sealing off the air in the area to be measured and monitoring changes in carbon dioxide concentration within the enclosed space to estimate the rate of carbon dioxide absorption or release. However, existing closed-box methods typically have the following problems:

[0004] Most current carbon dioxide flux measurement systems rely on manual operation to open and close the sampling chamber and manually adjust the sampling time and sampling period. This not only increases operational complexity but also easily leads to human error, affecting the accuracy and reliability of the measurement.

[0005] Because factors such as ambient temperature and humidity can affect carbon dioxide concentration measurements, traditional systems often cannot maintain high accuracy under dynamically changing environmental conditions. Excessive humidity can lead to condensation, which in turn affects the accuracy of carbon dioxide concentration measurements.

[0006] Existing carbon dioxide flux measurement systems are often fixed and cannot flexibly adjust the number of sampling points or the measurement cycle according to different experimental needs. However, the changes in carbon flux in ecosystems exhibit high spatial and temporal heterogeneity, thus requiring a system that can be configured according to actual needs.

[0007] Traditional carbon dioxide flux measurement systems often rely on complex hardware and extensive maintenance, and due to frequent sampling processes, they may require significant energy consumption to maintain normal operation.

[0008] However, existing technologies still suffer from insufficient automation, poor flexibility, and measurement errors in high humidity environments. Therefore, there is an urgent need for a carbon dioxide flux measurement system with higher automation, accuracy, and flexibility, capable of providing accurate and reliable measurement data under different environmental conditions, while also possessing strong scalability and adaptability to meet diverse ecological monitoring needs.

[0009] The fully automatic carbon dioxide flux measurement and assimilation system proposed in this utility model combines multiple advanced technologies such as automatic control, multi-port selector valve, real-time data acquisition and environmental regulation on the basis of existing technology. It aims to overcome the defects of existing technology, improve the accuracy, automation and reliability of carbon dioxide flux measurement, and provide an efficient, accurate and low-energy-consumption solution. Utility Model Content

[0010] 1. Technical problems to be solved

[0011] In view of the problems existing in the prior art, the purpose of this utility model is to provide a fully automatic carbon dioxide flux measurement and assimilation system, which can improve the accuracy, automation and reliability of carbon dioxide flux measurement, and provide an efficient, accurate and low-energy assimilation system.

[0012] 2. Technical Solution

[0013] To solve the above problems, the present invention adopts the following technical solution.

[0014] A fully automated carbon dioxide flux measurement and assimilation system includes:

[0015] Multiple fully automated opening and closing sampling boxes are used to seal the area to be tested;

[0016] A multi-port selector valve has multiple air inlets connected to the gas outlets of the multiple sampling boxes via air pipelines with a length not exceeding 5 meters and an inner diameter of 4 to 6 mm, respectively.

[0017] A greenhouse gas analyzer, the inlet of which is connected to the common outlet of the multi-port selector valve via a gas pipeline;

[0018] A data acquisition unit, and a temperature sensor, a humidity sensor, and a barometric pressure sensor electrically connected to the data acquisition unit; the temperature sensor, humidity sensor, and barometric pressure sensor are all located inside the sampling box for real-time acquisition of environmental data inside the box;

[0019] A touchscreen connected to the data acquisition unit is used to set and display the start and stop times and measurement parameters of each sampling box; and a system controller is electrically connected to the data acquisition unit, the multi-port selector valve, and the opening and closing drive mechanism and fan of each sampling box.

[0020] Based on the above characteristics, the system controller is configured to: control the multiple sampling boxes to open and close sequentially according to a preset cyclic sampling period T; after any sampling box is closed, control the multi-port selection valve to switch to the air inlet corresponding to that sampling box, and start the fan in the sampling box to agitate the air inside the box at a flow rate of 1 to 3 L / min; within a time window from the t1 second to the t2 second after the sampling box is closed, collect at least 3 carbon dioxide concentration data points through a greenhouse gas analyzer, and record the concentration change rate within this time window by a data acquisition device, and calculate the carbon dioxide flux according to the gas accumulation model of the closed box method.

[0021] In some embodiments, the body of the fully automatic opening and closing sampling box is made of transparent plexiglass or polycarbonate material, and its opening and closing action is achieved by the system controller through a stepper motor.

[0022] Based on the above characteristics, the system controller is also configured to automatically extend the closing time of the sampling box and start the anti-condensation program when the data acquisition device detects that the relative humidity in a sampling box exceeds 90%RH.

[0023] In some embodiments, the bottom of the fully automatic opening and closing sampling box is provided with a removable sealing base, which can be removed and installed to isolate the soil surface when soil respiration needs to be measured separately.

[0024] Based on the above features, the touchscreen is also configured to display the real-time status of each sampling box through a graphical interface, and allow users to adjust the sampling period and sampling time window as needed.

[0025] 3. Beneficial effects

[0026] Compared with existing technologies, the advantages of this utility model are:

[0027] 1) This invention integrates multiple fully automatic opening and closing sampling boxes and an advanced greenhouse gas analyzer, enabling the system to accurately measure carbon dioxide flux. The system can automatically switch gas sampling points via a multi-port selector valve, making the measurement process more efficient and highly accurate.

[0028] 2) The system utilizes high-precision sensors to ensure the high accuracy of the collected environmental data, which is crucial for calculating carbon dioxide flux. Accurate environmental data helps to correct carbon dioxide concentration data, avoid errors caused by environmental factors, and thus ensure the accuracy of carbon dioxide flux measurement.

[0029] 3) The system uses a sampling box made of transparent plexiglass or polycarbonate material to ensure that the measurement results are not interfered with under light conditions. The gas sampling pipe is no more than 5 meters long and has an inner diameter of 4-6 mm. This design not only ensures the stability of gas flow but also reduces the impact on the environment. In particular, it can maintain low energy consumption and maintenance requirements during long-term measurement.

[0030] 4) The system's modular design gives it strong scalability, allowing for flexible increases or decreases in the number of sampling boxes to meet different needs, making it suitable for ecological monitoring projects of varying scales. Through highly automated and high-precision environmental data acquisition, the system can provide accurate and reliable carbon dioxide flux data under different ecological conditions. Attached Figure Description

[0031] Figures 1-2 This is a schematic diagram of the structure of a fully automatic carbon dioxide flux measurement and assimilation system according to the present invention;

[0032] Figure 3 This is a scatter plot of RH changing over time for this utility model;

[0033] Figure 4 This is a scatter plot of P versus time for this utility model;

[0034] Figure 5 This is a scatter plot showing the change of [H2O]_ppm over time in this invention;

[0035] Figure 6 This is a scatter plot showing the [C02]d_ppm of this invention as a function of time.

[0036] Figure 7 This is a scatter plot showing the change of [CO2]_ppm over time in this invention.

[0037] Figure 8 This is a scatter plot of T versus time for this utility model.

[0038] Explanation of the labels in the diagram:

[0039] 1. Fully automatic opening and closing sampling box; 2. Multi-port selector valve; 3. Greenhouse gas analyzer; 4. Data logger; 5. Temperature sensor; 6. Humidity sensor; 7. Barometric pressure sensor; 8. Touch screen; 9. System controller; 10. Fan; 11. Base; 12. Stepper motor. Detailed Implementation

[0040] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0041] Example 1:

[0042] Please see Figure 1-2 A fully automated carbon dioxide flux measurement and assimilation system includes: multiple fully automated opening and closing sampling boxes 1 for sealing the area to be measured; a multi-port selection valve 2, whose multiple air inlets are connected to the gas outlets of the multiple sampling boxes 1 respectively through gas pipelines with a length not exceeding 5 meters and an inner diameter of 4 to 6 mm; and a greenhouse gas analyzer 3, whose air inlet is connected to the common outlet of the multi-port selection valve 2 through a gas pipeline.

[0043] A data acquisition unit 4, and a temperature sensor 5, a humidity sensor 6, and a pressure sensor 7, which are electrically connected to the data acquisition unit 4 respectively; the temperature sensor 5, humidity sensor 6, and pressure sensor 7 are all located inside the sampling box 1 and are used to collect environmental data inside the box in real time.

[0044] A touch screen 8 connected to the data acquisition unit 4 is used to set and display the start and stop times and measurement parameters of each sampling box 1; and a system controller 9 is electrically connected to the data acquisition unit 4, the multi-port selector valve 2, the opening and closing drive mechanism of each sampling box 1, and the fan 10.

[0045] The system controller 9 is configured to: control the plurality of sampling boxes 1 to open and close sequentially according to a preset cyclic sampling period T; after any sampling box 1 is closed, control the multi-port selection valve 2 to switch to the air inlet corresponding to the sampling box 1, and start the fan 10 in the sampling box 1 to agitate the air in the box at a flow rate of 1 to 3 L / min; within the time window from the t1 second to the t2 second after the sampling box 1 is closed, collect at least 3 carbon dioxide concentration data points through the greenhouse gas analyzer 3, and record the concentration change rate within the time window by the data acquisition unit 4, and calculate the carbon dioxide flux according to the gas accumulation model of the closed box method.

[0046] In some embodiments, the body of the fully automatic opening and closing sampling box 1 is made of transparent plexiglass or polycarbonate material, and its opening and closing action is achieved by the system controller 9 through a stepper motor 12. The system controller 9 is also configured to automatically extend the closing time of the box and activate the anti-condensation program when the data acquisition device 4 detects that the relative humidity inside a sampling box 1 exceeds 90%RH.

[0047] In some embodiments, the fully automatic opening and closing sampling box 1 has a removable sealing base 11 at its bottom. When soil respiration needs to be measured individually, vegetation can be removed and the base 11 installed to isolate the soil surface. The touch screen 8 is also configured to display the real-time status of each sampling box 1 through a graphical interface and allow users to adjust the sampling cycle and sampling time window as needed.

[0048] Working Principle: The system comprises multiple fully automatic opening and closing sampling boxes 1, each used to seal the area to be measured. The box body is made of transparent plexiglass or polycarbonate material to ensure that the measurement results are not interfered with under light conditions. Each sampling box is opened and closed by a system controller 9 via a stepper motor 12. During the sampling cycle, the sampling boxes open and close sequentially, and the gas environment inside each sampling box is accurately collected and recorded. Gas is introduced into a multi-port selection valve 2 through gas pipelines connected to multiple sampling boxes. This valve is responsible for switching the gas sampling ports of different sampling boxes. The length of the gas sampling pipeline does not exceed 5 meters, and the inner diameter is 4-6 mm, ensuring the stability of gas flow and the accuracy of measurement.

[0049] The system analyzes the incoming gas using a greenhouse gas analyzer 3, primarily collecting carbon dioxide (CO2) concentration data. The analyzer's inlet is connected to the common outlet of a multi-port selector valve, ensuring accurate CO2 concentration measurement after the gas passes through this inlet. The system connects to a temperature sensor 5, a humidity sensor 6, and a pressure sensor 7 via a data acquisition unit 4. These sensors are all located inside each sampling chamber to monitor environmental changes within the chamber in real time. This data is crucial for subsequent carbon dioxide flux calculations.

[0050] Within a designated time window after each sampling chamber closes (from second t1 to second t2), the greenhouse gas analyzer collects at least three carbon dioxide concentration data points. Using this data, the system calculates the rate of change of concentration and extrapolates the carbon dioxide flux based on the gas accumulation model of the closed-chamber method. This process is performed by data acquisition unit 4. The system calibrates the carbon dioxide concentration data based on the collected temperature, humidity, and air pressure data to ensure the accuracy of the measurement results. System controller 9 controls the opening and closing cycle of multiple sampling chambers and, after each sampling, activates fan 10 to agitate the air inside the sampling chamber. The fan flow rate is set to 1-3 L / min. The fan helps to uniformly mix the air inside the sampling chamber, avoiding uneven local gas concentrations and ensuring the representativeness of the measurement data. To address condensation issues that may occur in high humidity environments, the system is equipped with an anti-condensation program. When data acquisition unit 4 detects that the relative humidity of a sampling chamber exceeds 90% RH, the system automatically extends the closing time of that sampling chamber and activates the anti-condensation program. This measure avoids measurement errors caused by excessive humidity and ensures data reliability.

[0051] In certain measurement scenarios, particularly when measuring soil respiration, vegetation inside the sampling chamber can be removed and a removable, sealed base 11 installed. This base isolates the soil surface, ensuring that the measured carbon dioxide flux originates solely from soil respiration and is unaffected by external vegetation.

[0052] The system is equipped with a touchscreen 8, which allows users to view the start and stop times of each sampling chamber and the corresponding measurement parameters in real time through a graphical interface. In addition, the touchscreen allows users to set parameters such as sampling period, humidity threshold, and fan speed, and can display measurement data, calculation results, and system status.

[0053] The entire system operates with a high degree of automation. Users only need to set parameters via the touchscreen; other operations, such as switching sampling chambers, gas sampling, data recording, and fan control, are all automatically completed by the system controller 9. The system also features an intelligent feedback mechanism that can adjust various parameters during the sampling process based on real-time monitoring data, ensuring stable and efficient data acquisition.

[0054] Example 2: Carbon Dioxide Flux Measurement System Based on Multi-Port Selector Valve

[0055] 1. Experimental setup

[0056] This embodiment employs the fully automated carbon dioxide flux measurement and assimilation system described in the above technical disclosure. The system includes multiple fully automated opening and closing sampling boxes 1, a multi-port selector valve 2, a greenhouse gas analyzer 3, a data logger 4, a temperature and humidity sensor 5, and a pressure sensor 7. The sampling boxes are made of transparent plexiglass, and the gas pipeline length does not exceed 5 meters with an inner diameter of 4–6 mm, ensuring gas flow stability and measurement accuracy.

[0057] 2. Experimental Procedure

[0058] Start the system and set the sampling period T=30 minutes, with the on / off cycle of each sampling box set to 5 minutes. The system controller 9 controls multiple sampling boxes to open and close sequentially in a preset order.

[0059] During the time window after the sampling box is closed (from t1=10 seconds to t2=30 seconds), carbon dioxide concentration data points are collected by greenhouse gas analyzer 3.

[0060] At least three carbon dioxide concentration data points are collected each time to ensure data accuracy. Assume that within this time window, the CO2 concentration data measured by the analyzer are as follows:

[0061] CO2 concentration (C1) = 420 ppm

[0062] CO2 concentration (C2) = 430 ppm

[0063] CO2 concentration (C3) = 440 ppm

[0064] Temperature, humidity, and air pressure sensors detected a temperature of 24°C, a humidity of 70% RH, and an air pressure of 1013 hPa inside the sampling chamber.

[0065] 3. Calculation of carbon dioxide flux

[0066] Based on the gas accumulation model of the closed-box method, the formula for calculating carbon dioxide flux (F) is as follows:

[0067]

[0068] Where: 𝑉 is the volume of the sampling box (assumed to be 0.1m³), and 𝐴 is the opening area of ​​the sampling box (assumed to be 0.02m²). , This is the collected carbon dioxide concentration data (unit: ppm). , It represents the start and end times of the sampling time window (in seconds).

[0069] Calculation results:

[0070] 2.5L / m 2 / s.

[0071] The experimental results show that, under the specified sampling conditions, the carbon dioxide flux is 2.5 L / m² / s.

[0072] 4. Experimental Data Recording

[0073] The following real-time data was collected using data collector 4:

[0074] Sampling chamber temperature: 24°C; relative humidity: 70%RH; air pressure: 1013hPa; carbon dioxide concentration: 420ppm, 430ppm, 440ppm.

[0075] These data are automatically recorded and displayed on the touchscreen 8, allowing users to adjust parameters such as sampling period and wind speed based on real-time data.

[0076] Example 3: Automated Carbon Dioxide Flux Measurement System for Soil Respiration Measurement

[0077] 1. Experimental setup

[0078] In this embodiment, the fully automated carbon dioxide flux measurement and assimilation system described above is used, and a removable sealed base 11 is installed at the bottom of the sampling box 1 to facilitate independent measurement of soil respiration. During the experiment, vegetation in the sampling box is removed, leaving only the soil layer. Other system components and operations are the same as in Embodiment 1.

[0079] 2. Experimental Procedure

[0080] Start the system and set the sampling period T=60 minutes, with the on / off cycle of each sampling box set to 10 minutes. The system controller 9 controls multiple sampling boxes to open and close sequentially in a preset order.

[0081] During the time window after the sampling box is closed (from t1=15 seconds to t2=45 seconds), carbon dioxide concentration data points are collected by greenhouse gas analyzer 3.

[0082] At least three carbon dioxide concentration data points are collected each time. Assume the collected CO2 concentration data are as follows:

[0083] CO2 concentration (C1) = 380 ppm

[0084] CO2 concentration (C2) = 390 ppm

[0085] CO2 concentration (C3) = 400 ppm

[0086] The data collected by the sensor are as follows: Temperature: 20°C; Humidity: 80%RH; Air pressure: 1015hPa.

[0087] 3. Calculation of carbon dioxide flux

[0088] Based on the gas accumulation model of the closed-box method, the formula for calculating carbon dioxide flux (F) is as follows:

[0089]

[0090] Where: 𝑉 is the volume of the sampling box (assumed to be 0.1m³), and 𝐴 is the opening area of ​​the sampling box (assumed to be 0.02m²). , This is the collected carbon dioxide concentration data (unit: ppm). , It represents the start and end times of the sampling time window (in seconds).

[0091] Calculation results:

[0092] 1.67L / m 2 / s.

[0093] The experimental results show that, under the specified sampling conditions, the carbon dioxide flux is 1.67 L / m² / s.

[0094] 4. Experimental Data Recording

[0095] The following real-time data was collected using data collector 4:

[0096] Sampling chamber temperature: 20°C; relative humidity: 80%RH; air pressure: 1015hPa; carbon dioxide concentration: 380ppm, 390ppm, 400ppm.

[0097] These data are automatically recorded and displayed on the touchscreen 8, allowing users to adjust parameters such as sampling period and wind speed based on real-time data.

[0098] Depend on Figure 3 As can be seen, the relative humidity (RH) change curve over time in this invention represents the humidity fluctuation of the internal environment of each sampling box 1. This is closely related to the humidity sensor 6 in the system design, which monitors the humidity inside the box in real time and adjusts the sampling cycle or controls the anti-condensation program based on this data (when the humidity exceeds 90%RH).

[0099] System control and sampling chamber opening and closing: The periodic fluctuations (increase and decrease in humidity) shown in the diagram are related to the opening and closing operations of the sampling chambers. The system controller 9 controls the opening and closing of the sampling chambers according to a preset cycle. The opening and closing cycle of each sampling chamber may correspond to the fluctuation cycle shown in the diagram, ensuring that each chamber samples gas within a predetermined time.

[0100] Data recording and analysis: The graph shows the humidity changes at different time points. This data is used to further calculate carbon dioxide flux and help the system analyze gas exchange under different environmental conditions.

[0101] Anti-condensation program: When the humidity approaches or exceeds a certain value, the system will activate the anti-condensation program (as shown in the higher humidity range in the figure). This is consistent with the system's function of automatically extending the shutdown time to avoid condensation affecting the accuracy of data acquisition.

[0102] Depend on Figure 4 As can be seen, P (vertical axis) represents carbon dioxide concentration; time (horizontal axis) shows the time period from 12:00 to 15:00, with data points distributed along this time period.

[0103] Shaded areas: Represent different operating states of the system – “OPEN” (blue) and “CLOSE” (pink). These represent the open / closed state of the sampling box at different times, corresponding to the system's operating mode.

[0104] Data point (small dot): Displays the actual measurement data recorded at a specific point in time.

[0105] This time-series scatter plot helps visualize the system's performance, showing the relationship between different states (OPEN or CLOSE) and measurements during operation.

[0106] As the sampling chamber alternates between open and closed, the data points reflect the changes in carbon dioxide concentration or other relevant parameters over time, exhibiting stable or fluctuating patterns in carbon dioxide concentration that change as the system adjusts. The timing of the "OPEN" and "CLOSE" states (corresponding to the operating states of the sampling chamber and valves) is key to understanding how the system analyzes soil and ecosystem respiration.

[0107] Depend on Figure 5 As can be seen, the horizontal axis represents time, from 12:00 to 15:00, in hours and minutes, showing the change in H2O concentration over three hours.

[0108] The vertical axis represents the H2O concentration, measured in ppm. ppm (parts per million) is a common unit for moisture concentration, indicating the amount of water present.

[0109] Color-coded status (OPEN and CLOSE):

[0110] Pink (OPEN): At this stage, the gas or sample container is open. In this state, the H2O concentration increases.

[0111] Blue (CLOSE): In this stage, the gas or sample container is off, and the H2O concentration decreases. In other words, in the off state, the system may have stopped or reduced sampling or exchange with the environment.

[0112] Between each "OPEN" and "CLOSE" state, the H2O concentration exhibited a clear periodic variation. This fluctuation was related to changes in equipment operation or environmental factors. In the OPEN state, ventilation or aeration led to an increase in moisture concentration, while in the CLOSE state, it was a result of moisture evaporation or consumption after the sample was sealed.

[0113] Within each cycle, the H2O concentration first increases rapidly to a peak, then drops sharply, eventually returning to a lower baseline level.

[0114] Data points are represented by dark dotted lines, indicating that measurements were taken at each time point, and that the data fluctuated significantly across different time points. Specific time points (such as 12:30, 13:30, and 14:30) are clearly marked on the graph, indicating that the chart records high-frequency sampling data.

[0115] This fluctuation pattern is likely related to the operating mechanism of the described "fully automated carbon dioxide flux measurement and assimilation system." This system utilizes different sampling chambers (e.g., chamber 1, chamber 2, etc.), opening and closing these chambers at different times, and controlling gas flow within the chambers via fans. The H2O concentration changes shown in the graph are likely closely related to these operations. For example:

[0116] When the sampling box is in "OPEN" mode, it is in ventilation or sampling mode, and the H2O concentration will increase.

[0117] In the "CLOSE" state, the sampling chamber is closed, and moisture evaporates or decreases, resulting in a drop in concentration.

[0118] Depend on Figure 6 As can be seen, the fully automatic opening and closing sampling chamber is the core component of the system. Each sampling chamber is equipped with a high-precision sensor to monitor environmental data such as temperature, humidity, and air pressure. Each sampling chamber operates independently, opening and closing automatically to ensure that gas samples are collected one by one in the set sequence.

[0119] Multi-port selector valve: This valve connects each sampling chamber to the greenhouse gas analyzer via piping. The six-port selector valve controls the switching of the inlet channels, ensuring that only one sampling chamber samples gas at a time.

[0120] Greenhouse gas analyzer: Used to analyze gas data collected through the sampling box, especially CO2 concentration, to provide data support for subsequent flux calculations.

[0121] Data acquisition system: Collects data from temperature, humidity, and air pressure sensors in real time, and interfaces with gas analysis data to analyze ecosystem respiration (Reco).

[0122] During system operation, users can set the opening and closing times of each sampling chamber via the touchscreen. The system will open and close the sampling chambers one by one according to the preset program. Each time a sampling chamber is closed, it will be ventilated to ensure that the CO2 concentration inside returns to atmospheric levels. Specifically, sampling chamber 1 is closed, sampling chambers 2-4 are opened, the six-port valve switches to one intake port, and the system begins sampling. Every certain period of time (e.g., every ten minutes), the sampling chambers will switch to ensure the uniformity of data sampling and the efficient operation of the system.

[0123] The charts show the changes in CO2 concentration over time (e.g., between 12:00 and 15:00). It can be seen that the CO2 concentration fluctuates periodically with the opening and closing of each sampling chamber. The changes in each period are closely related to the opening and closing of the sampling chambers.

[0124] The time period in the graph: The time axis is divided into different time periods, with "OPEN" and "CLOSE" states marked by color. Each switching of the sampling chamber causes a sharp change in CO2 concentration, reflecting the dynamic response of the system under different states.

[0125] Data points: Each data point represents the CO2 concentration data collected at a specific moment. The different operating states of the sampling chambers are closely related to the changes in data points, and the data exhibits a periodic fluctuation of "rise-fall," which is consistent with the dynamic changes in respiration in the ecosystem.

[0126] The system is highly automated and can control the opening and closing of the sampling box according to the set program, which greatly reduces human intervention and improves the efficiency and accuracy of data collection.

[0127] The sampling box is designed to sample independently. The state (OPEN or CLOSE) of each sampling box is automatically adjusted, and the system automatically transmits the collected data to the data acquisition unit within each sampling period to ensure the continuity and real-time nature of the data.

[0128] High-precision sensors can effectively improve the accuracy of measurements, especially when monitoring environmental factors such as temperature, humidity and air pressure, and are of great significance for the determination of CO2 concentration.

[0129] Depend on Figure 7 It is known that the system has multiple sampling boxes, each equipped with temperature, humidity and air pressure sensors to monitor and record environmental conditions in real time.

[0130] After startup, chamber 1 enters the closed state and starts its fan for air circulation, while the other sampling chambers (chambers 2 to 4) remain open with their fans off. At this point, the six-port selector valve directs airflow into chamber 1 to begin sampling.

[0131] The system switches sampling chambers at set intervals (set via touchscreen). For example, after 10 minutes of operation, chamber 1 opens, the fan stops, and ventilation continues until the CO2 concentration returns to atmospheric levels. As chamber 1 opens, chamber 2 closes and begins sampling, the airflow switches to chamber 2, and the fan starts operating. The system continues this cycle, switching sampling chambers sequentially until all chambers have completed sampling.

[0132] Temperature, humidity, and air pressure data from each sampling chamber are transmitted to the data logger in real time. This data is used to analyze and calculate CO2 emissions from the ecosystem. The system can measure not only the respiration of aboveground plant parts (i.e., CO2 release from the plant body), but also soil respiration (including root respiration and microbial respiration) by removing vegetation from the base.

[0133] The CO2 concentration in the graph changes over time, exhibiting periodic fluctuations. These fluctuations are closely related to the sampling chamber switching cycle and ventilation control. The change in CO2 concentration after each sampling chamber switch reflects the change in the internal environmental conditions of that chamber. Color differentiation (pink and blue) indicates "OPEN" and "CLOSE" states, used to identify the system's operating status at different times.

[0134] Depend on Figure 8 As can be seen from the graph, the temperature changes are closely related to the opening and closing states of multiple sampling boxes within the system. The opening and closing cycle and operating status (open or closed) of each sampling box directly affect the temperature data. The system controls the start and stop times of each sampling box via a touchscreen. Different sampling boxes are in different operating states at different times.

[0135] When chamber 1 is closed, the fan starts running, while the other sampling chambers (such as chambers 2, 3, and 4) remain open. Over time, the system will sequentially open or close different sampling chambers, adjusting the gas sampling and analysis cycle through these actions.

[0136] Temperature rise phase (12:00 - 13:00):

[0137] Initially, sampling chamber 1 is in a closed state, and the internal temperature of the system gradually increases, possibly due to poor gas circulation inside the chamber or the influence of external temperature. This gradual temperature increase during this stage demonstrates the impact of the sampling chamber's closed state and fan operation on the internal temperature of the system.

[0138] During this period, sampling boxes 2-4 may be in an open state, with airflow entering the boxes and being affected by the gas exchange inside the system, thereby regulating the temperature.

[0139] Temperature stabilization and decline phase (13:00 - 15:00):

[0140] As Chamber 1 is opened, the carbon dioxide concentration inside begins to return to atmospheric levels, the fan stops running, and Chamber 2 closes, allowing the sampling process to continue. During this phase, the temperature gradually decreases, possibly due to air exchange and environmental conditions, until the temperature inside the chamber gradually matches the outside temperature.

[0141] The pink and blue areas in the background of the diagram mark the time periods for the OPEN and CLOSE states. These background colors may be used to distinguish different work cycles.

[0142] Pink indicates the closed state (CLOSE), meaning the sampling box is closed and ventilation or gas exchange has begun.

[0143] Blue indicates the OPEN state, meaning the sampling chamber is collecting data, the fan is off, and the gas flow is relatively stable.

[0144] Black data points: These points represent temperature data collected at different time points. By observing these data points, we can understand the temperature changes of the system under different operating conditions, helping to analyze the efficiency of the sampling chamber and the accuracy of temperature control.

[0145] This system can measure not only the respiration of an ecosystem (including both above-ground and below-ground plant parts), but also soil respiration separately by removing plant parts. By monitoring this respiration data, we can gain further insight into how plants and soil interact with the environment through CO2 exchange, providing data support for ecological research.

[0146] The above description is merely a preferred embodiment of this utility model; however, the protection scope of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in this utility model, based on the technical solution and its improved concept, should be included within the protection scope of this utility model.

Claims

1. A fully automated carbon dioxide flux measurement and assimilation system, characterized in that, include: Multiple fully automatic opening and closing sampling boxes (1) are used to seal the area to be tested; A multi-port selector valve (2) has multiple air inlets connected to the gas outlets of the multiple sampling boxes (1) respectively through air pipelines with a length not exceeding 5 meters and an inner diameter of 4 to 6 mm; A greenhouse gas analyzer (3) has its inlet connected to the common outlet of the multi-port selector valve (2) via a gas pipeline; A data acquisition unit (4), and a temperature sensor (5), a humidity sensor (6) and a pressure sensor (7) electrically connected to the data acquisition unit (4); the temperature sensor (5), humidity sensor (6) and pressure sensor (7) are all located inside the sampling box (1) for real-time acquisition of environmental data inside the box; A touch screen (8) connected to the data acquisition unit (4) is used to set and display the start and stop times and measurement parameters of each sampling box (1); And a system controller (9) is electrically connected to the data acquisition unit (4), the multi-port selector valve (2), the opening and closing drive mechanism of each sampling box (1), and the fan (10).

2. The fully automated carbon dioxide flux measurement and assimilation system according to claim 1, characterized in that: The system controller (9) is configured to: control the plurality of sampling boxes (1) to open and close sequentially according to a preset cyclic sampling period T; after any sampling box (1) is closed, control the multi-port selection valve (2) to switch to the air inlet corresponding to the sampling box, and start the fan (10) in the sampling box to agitate the air in the box at a flow rate of 1 to 3 L / min; within the time window from the t1 second to the t2 second after the sampling box (1) is closed, collect at least 3 carbon dioxide concentration data points through the greenhouse gas analyzer (3), and record the concentration change rate within the time window by the data acquisition device (4), and calculate the carbon dioxide flux according to the gas accumulation model of the closed box method.

3. The fully automated carbon dioxide flux measurement and assimilation system according to claim 1, characterized in that: The fully automatic opening and closing sampling box (1) is made of transparent organic glass or polycarbonate material, and its opening and closing action is achieved by the system controller (9) through the stepper motor (12).

4. The fully automated carbon dioxide flux measurement and assimilation system according to claim 1, characterized in that: The system controller (9) is also configured to automatically extend the closing time of a sampling box (1) and start an anti-condensation program when the data acquisition unit (4) detects that the relative humidity in a sampling box (1) exceeds 90%RH.

5. The fully automated carbon dioxide flux measurement and assimilation system according to claim 1, characterized in that: The bottom of the fully automatic opening and closing sampling box (1) is provided with a detachable sealing base (11). When soil respiration needs to be measured separately, the vegetation can be removed and the base (11) can be installed to isolate the soil surface.

6. The fully automated carbon dioxide flux measurement and assimilation system according to claim 1, characterized in that: The touchscreen (8) is also configured to display the real-time status of each sampling box (1) through a graphical interface and allow users to adjust the sampling period and sampling time window as needed.

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