An automated plant net carbon fixation capacity determination system and determination method

Abstract

The present invention belongs to the technical field of measuring the net carbon fixation capacity of plants, and specifically is an automated system and method for measuring the net carbon fixation capacity of plants. It includes a plant artificial photosynthesis incubator controlled by a host computer IPC and PLC controller, a gas supply and exhaust unit, and a gas online continuous automatic monitoring unit. The plant artificial photosynthesis incubator includes an outer shell, a sealed inner working chamber is arranged inside the outer shell, and an LED light source, a temperature sensor, a humidity sensor, a pressure sensor, and a constant temperature and humidity regulating device are arranged inside the inner working chamber. The gas supply and exhaust unit includes an air intake device and an exhaust device connected to the inner working chamber; the gas online continuous automatic monitoring unit includes a first gas solenoid valve, a second gas solenoid valve, an online infrared analysis device, and an online gas chromatography analysis device. The present invention has two experimental systems for plant photosynthesis carbon fixation and carbon emission in the process of litter decomposition, which promotes the accuracy of the measurement data; and simplifies the existing operating steps of such experiments.

Description

Technical Field

[0001] The present invention belongs to the technical field of plant net carbon fixation capacity determination, and specifically relates to an automated plant net carbon fixation capacity determination system and determination method. Background Art

[0002] In order to cope with the environmental problem of global warming, improving the carbon fixation capacity of plants is one of the ways to reduce greenhouse gas emissions. Plant photosynthesis converts CO2 into a variety of organic matter and fixes it in the body, providing materials and energy for its growth. It is the basic link in the growth and development process and has great carbon sink capacity. It plays an important role in regulating the balance of atmospheric CO2 and O2 and improving the carbon fixation and storage capacity of ecosystems. With the increase of CO2 concentration in the atmosphere, the scale of plant carbon sinks is gradually expanding. However, CO2 and CH4 produced during the decomposition of litter are important sources of greenhouse gases. It can be seen that the growth and development process of plants has both "carbon sink" and "carbon source" functions. Accurately understanding the net carbon fixation capacity of plants is of great significance to improving the uncertainty of carbon accounting at the global or regional scale and balancing the global carbon budget. It also has a practical effect on the realization of my country's carbon neutrality goals.

[0003] There are many methods for measuring the net carbon fixation capacity of plants, such as the plot inventory method, eddy covariance method, box method, etc. The plot inventory method mainly calculates the carbon storage by estimating the plant biomass, which can determine the carbon fixation capacity of plants over a long period of time. However, there are problems such as difficulty in collecting plant samples, subjective restrictions on plot selection, and large workload, which make it difficult to estimate plant biomass. There are also errors in the estimation between biomass and carbon storage, and the accuracy of the data is difficult to guarantee. Based on the maturity of remote sensing technology, the method of estimating carbon storage through remote sensing data has also become the main research direction. The eddy covariance method observes the net ecosystem productivity of plants by directly measuring the CO2 eddy transfer rate above the plants, thereby evaluating their carbon source / sink capacity. It is simple to operate and can achieve continuous and long-term monitoring of specific ecosystems. However, this method requires expensive and sophisticated instruments and analysis software, and when the CO2 eddy rate of the air is slow, the measured data error is large. At the same time, this method is not suitable for the determination of the carbon fixation capacity of individual plants; the box method estimates the carbon fixation capacity of plants by the changes in CO2 and CH4 concentrations in a sealed space in a short period of time. It has the advantages of convenient installation, simple operation, and high sensitivity. It is the main method for studying the changes in carbon flux of low plants such as farmland and grassland. However, the presence of the sealed box during the measurement process weakens the spatial variability of the gas, and the box itself will also interfere with the environment of the sampling area, such as temperature, humidity, air flow, pressure, etc., affecting the accuracy of the data. In summary, there are still certain shortcomings in the current methods for determining the carbon fixation capacity of plants, and no system has been found that can measure the net carbon fixation capacity of plants throughout their life cycle.

[0004] In view of this, and in view of the fact that plants have dual functions as carbon sinks and carbon sources during their growth and development, the present invention provides an automated system for determining the net carbon fixation capacity of plants. Summary of the invention

[0005] The present invention provides an automated system and method for determining the net carbon fixation capacity of plants in order to determine both the amount of carbon fixed during plant growth and the amount of carbon emitted during litter decomposition, and to further illustrate the net carbon fixation capacity of plants by comparing the characteristics of plant carbon fixation and its litter carbon emission.

[0006] The present invention adopts the following technical scheme: an automated plant net carbon fixation capacity determination system, comprising a plant artificial photosynthesis incubator controlled by a host computer IPC and a PLC controller, a gas supply and exhaust unit, and a gas online continuous automatic monitoring unit. The plant artificial photosynthesis incubator comprises an outer shell, a sealed inner working room is arranged in the outer shell, and an LED light source, a temperature sensor, a humidity sensor, a pressure sensor, and a constant temperature and humidity regulating device are arranged inside the inner working room. The temperature sensor, the humidity sensor, and the pressure sensor transmit the temperature, humidity, and pressure signals of the inner working room to the PLC controller at any time, and display them on the host computer IPC. The gas supply and exhaust unit comprises an air intake device and an exhaust device connected to the inner working room; the gas online continuous automatic monitoring unit comprises a first gas solenoid valve, a second gas solenoid valve, an online infrared analysis device, and an online gas chromatography analysis device, and the air intake ends of the first gas solenoid valve and the second gas solenoid valve are connected to the exhaust device; the exhaust ends are respectively connected to the online infrared analysis device and the online gas chromatography analysis device; the online infrared analysis device and the online gas chromatography analysis device are connected to the air intake device through pipelines.

[0007] Furthermore, the air intake device includes a carrier gas cylinder, an air intake pump, a first electromagnetic three-way valve, a first gas flow meter and an air intake hole arranged on the inner working chamber, which are connected in sequence by pipelines.

[0008] Furthermore, the online infrared analysis equipment and the online gas chromatography analysis equipment are connected to the first electromagnetic three-way valve of the air intake device through pipelines.

[0009] Furthermore, the exhaust device includes a sampling probe, an exhaust hole, an exhaust pump, a second electromagnetic three-way valve and a second gas flow meter. The sampling probe is arranged in the inner working chamber, the exhaust hole is arranged on the working chamber, the sampling probe is connected to the exhaust hole, and the exhaust hole is connected to the second gas flow meter, the exhaust pump and the second electromagnetic three-way valve in sequence.

[0010] Furthermore, the second electromagnetic three-way valve is connected to the first gas electromagnetic valve and the second gas electromagnetic valve.

[0011] Furthermore, a plexiglass window is provided on the inner studio.

[0012] Furthermore, the LED light source has built-in light-emitting diodes of four wavelengths: red, white, blue and green, and also includes an ultraviolet lamp.

[0013] Furthermore, the constant temperature and humidity regulating device comprises a refrigeration unit, a heating system, a humidification system and a dehumidification system. The constant temperature and humidity regulating device is placed between the outer shell and the inner working chamber and communicates with the inner working chamber.

[0014] A method for determining the net carbon fixation capacity of plants by an automated system comprises the following steps:

[0015] S100: The temperature sensor, humidity sensor and pressure sensor monitor the environmental conditions of the working room in the incubator in real time, transmit the signal to the PLC controller, and display it on the host computer IPC.

[0016] S200: When the temperature or humidity of the inner working room is lower than or higher than the set value, the PLC controller receives the signal from the temperature sensor or humidity sensor, and controls the constant temperature and humidity adjustment device to adjust the temperature or humidity of the inner working room so that the temperature or humidity of the inner working room reaches the set value; when the pressure exceeds the set value, the PLC controller controls the air intake device and the exhaust device according to the signal of the pressure sensor until the pressure of the inner working room reaches the set value.

[0017] S300: The vacuum pump is turned on at regular intervals, and the sample gas is extracted from the exhaust device and enters the gas online continuous automatic monitoring unit to measure the concentration of different gases and transmit the data to the upper computer IPC.

[0018] S400: When the gas concentration exceeds the set value, the PLC controller controls the air intake device and the exhaust device until the gas concentration in the inner working chamber returns to the set value. The gas analyzed by the online continuous automatic monitoring unit re-enters the inner working chamber through the air intake device to keep the gas composition in the inner working chamber unchanged.

[0019] S500: Numerical calculation of plant net carbon fixation capacity:

[0020] After analysis by online infrared analysis equipment, the CO2 mass absorbed by the net photosynthesis of plants and the CO2 emission from the decomposition of plant litter can be obtained; after measurement by online gas chromatography analysis equipment, the CH4 emission from the decomposition of plant litter can be obtained respectively; the calculation method of the net carbon fixation capacity of plants is:

[0021]

[0022] Where: M represents the net carbon fixation capacity of plants; 12 / 44 represents the coefficient of CO2 conversion to C; S jrepresents the mass of CO2 absorbed by plants through net photosynthesis in j days; L t1 L represents the CO2 emission from the decomposition of dry matter grown by plants in time j within time t; t2 represents the CH4 emission from the decomposition of dry matter grown by plants in time j during time t; 25 represents the coefficient of conversion of CH4 into CO2 equivalent.

[0023] Compared with the prior art, the present invention has the following beneficial effects: the experiment is carried out in a sealed plant artificial photosynthesis incubator, the measured data is more accurate, and the presence of LED light sources, temperature sensors, humidity sensors, pressure sensors and constant temperature and humidity adjustment devices in the incubator can keep the environment in the incubator stable, solving the problems of poor development, retardation or death in the plant cultivation process; the gas supply and exhaust unit can realize the automation of gas regulation in the incubator, maintain the stability of gas concentration and pressure in the incubator, and the gas online continuous automatic monitoring unit can continuously and automatically analyze the sample gas in the incubator for a long time, and the operation is continuous and stable.

[0024] The present invention combines two experimental systems, namely, carbon fixation by plant photosynthesis and carbon emission in the process of litter decomposition, with stable operation and strong controllability, which effectively promotes the accuracy of measured data; moreover, it simplifies the operation steps of existing experiments of this type, and avoids errors caused by human operation or mistakes; at the same time, the use of a PLC controller and an upper computer IPC can make the entire system process simple, automatic, and intuitive, and the data processing is accurate and the display is timely, and it has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention;

[0026] Figure 2 A schematic diagram of data transmission and control of the present invention;

[0027] In the figure: 1---incubator shell; 2---LED light source; 3---sealed inner working room; 4---plexiglass window; 5---sampling probe; 6---temperature sensor; 7---humidity sensor; 8---experimental sample; 9---intake pump; 10---first electromagnetic three-way valve; 11---first gas flowmeter; 12---carrier gas cylinder; 13---gas; 14---constant temperature and humidity adjustment device; 15---inlet hole; 16---exhaust hole; 17---second gas flowmeter; 18---exhaust pump; 19---second electromagnetic three-way valve; 20---pressure sensor; 21---first gas electromagnetic valve; 22---online infrared analysis equipment; 23---second gas electromagnetic valve; 24---online gas chromatography analysis equipment; 25---PLC controller; 26---host computer IPC. DETAILED DESCRIPTION

[0028] The following is attached to the instruction manual Figure 1 and 2 Further explain this system.

[0029] The invention discloses an automatic plant net carbon fixation capacity determination system, which is composed of a plant artificial photosynthesis incubator controlled by a host computer IPC26 and a PLC controller 25, a gas supply and exhaust unit and a gas online continuous automatic monitoring unit.

[0030] The host computer IPC26 is equipped with an LCD industrial tablet computer, which has the functions of displaying collected data (temperature, humidity, pressure, flow, CO2 concentration, O2 concentration and CH4 concentration), setting various parameters of the incubator environment (temperature, humidity, pressure, gas concentration), completing maintenance and diagnostic operations of various parts in the device, and editing instrument parameters and analysis methods. The large-screen touch screen mode is adopted, and the screen makes the experimental operation simple and the editing convenient. The interface is available in Chinese and English, and the data change curve and data can be displayed on the screen. It has an automatic calculation function, and can immediately correct the changes in temperature, humidity, CO2 and CH4 concentrations, making the control more accurate and stable.

[0031] The PLC controller 25 receives signals of various gas concentrations (CO2 concentration, O2 concentration and CH4 concentration), temperature, humidity, pressure and flow, performs deep data processing through software, and transmits the processed data to the host computer IPC25. At the same time, this component is also the master controller of the entire device, which can control the switch status of other units or devices according to the received signals, providing rich functions and higher reliability and expansion capabilities.

[0032] The plant artificial photosynthesis incubator is composed of a shell 1, a sealed inner studio 3, an LED light source 2, a plexiglass window 4, a temperature sensor 6, a humidity sensor 7, a pressure sensor 20 and a constant temperature and humidity adjustment device 14; the LED light source 2 is equipped with red, white, blue and green four-band light-emitting diodes and ultraviolet lamps for plant illumination, and is installed on the top of the inner studio of the incubator. The light intensity can be automatically adjusted, and the ultraviolet lamp can regularly disinfect and sterilize the inner studio 3 to ensure the cleanliness of the enclosed space. The temperature sensor 6, humidity sensor 7 and pressure sensor 20 are installed on the left and right sides of the inner studio 3 of the incubator; the constant temperature and humidity adjustment device 14 is composed of a refrigeration unit (refrigerant, refrigerator, drying filter, fan), a heating system (stainless steel tube with heat dissipation fins), a humidification system (steam electric heating wire coil), and a dehumidification system (compressor), which are placed between the incubator shell 1 and the inner studio 3, and communicated with the inner studio 3. The TMHM constant temperature and constant room adjustment method is used to keep the environment of the inner studio stable. The sealed inner working room 3 adopts the laser internal and external welding process of the inner cavity, which is sealed without leakage. The material is a stainless steel mirror inner liner with semicircular arc transitions at the four corners. It has an automatic cleaning function. At the same time, partitions of suitable sizes can be selected and installed in the inner working room to realize the free division of the space inside the box.

[0033] The temperature sensor 6, humidity sensor 7 and pressure sensor 20 transmit the temperature, humidity and pressure signals of the inner working room to the PLC controller 25 at any time, and display them on the host computer IPC26. However, when the temperature or humidity of the inner working room 3 is lower than or higher than the set value, the PLC controller 25 receives the signal and controls the constant temperature and humidity regulating device 14 to regulate the temperature or humidity of the inner working room 3 so that the temperature and humidity of the inner working room 3 reach the set value; when the pressure exceeds the set value, the PLC controller 25 controls the switch state of the gas supply and exhaust unit and monitors the gas flow according to the signal of the pressure sensor 20 until the pressure of the inner working room 3 reaches the set value.

[0034] The gas supply and exhaust unit is composed of an air intake device and an exhaust device, wherein the air intake device is composed of a carrier gas cylinder 12, an air intake pump 9, a first electromagnetic three-way valve 10, a first gas flow meter 11 and an air intake hole 15 connected in sequence by pipelines, and the exhaust device is composed of a sampling probe 5, an air extraction hole 16, an air extraction pump 18, a second electromagnetic three-way valve 19 and a second gas flow meter 17 connected in sequence by pipelines; the sampling probes 5 are placed on the left and right walls of the inner working room of different lengths, and can collect sample gases from all directions of the inner working room 3 for measurement, and are connected to the air extraction hole 16 on the upper wall of the right side of the incubator through a pipeline, and the other end of the air extraction hole 16 is connected to the exhaust device outside the incubator through a pipeline; an air intake hole 15 is installed on the lower wall of the left side of the incubator, and the air intake hole 15 is connected to the air intake device outside the box, and the carrier gas cylinder 12 can be replaced as needed.

[0035] The gas online continuous automatic monitoring unit is composed of a first gas solenoid valve 21, a second gas solenoid valve 23, an online infrared analysis device 22 and an online gas chromatography analysis device 24 connected by pipelines; the air inlet ends of the first gas solenoid valve 21 and the second gas solenoid valve 23 are connected to the second electromagnetic three-way valve 19, and the exhaust ends are connected to the online infrared analysis device 22 and the online gas chromatography analysis device 24 respectively; the online infrared analysis device 22 and the online gas chromatography analysis device 24 are connected to the first electromagnetic three-way valve 10 through pipelines, so that the analyzed gas re-enters the working room 3 in the incubator, keeping the gas composition of the inner working room 3 unchanged.

[0036] The gas online continuous automatic monitoring unit is used to analyze the CO2, O2 and CH4 concentrations of the collected sample gas, and transmit the above information to the PLC controller 25 for display on the host computer IPC26. When the CO2, O2 and CH4 concentrations exceed or fall below the set value, the PLC controller 25 receives the signal and controls the switch state of the gas supply and exhaust unit, monitors the gas flow, until the gas concentration in the inner working room 3 returns to the set value. It has maintenance calibration, fault diagnosis, alarm function, automatic data calibration and wireless data transmission function.

[0037] The online infrared analysis equipment adopts NDIR technology to detect non-dispersive infrared gas of CO2, which can accurately monitor low concentration of CO2 and eliminate the interference of other gases. The absorption spectrum of the gas to be tested is obtained by comparing the difference of the absorption of the radiation of the specific light source by the gas molecules to be tested with the original light intensity, so as to qualitatively and quantitatively analyze the composition and content of the gas absorbed in this band.

[0038] First, the relationship between I and I0 is obtained from the Lambert-Beer law, as shown in formula (1):

[0039] I(λ)=I0(λ)e (-Lσ(λ)c)(1)

[0040] Where: λ represents the wavelength of the spectrum; I(λ) represents the outgoing light intensity; I0(λ) represents the incident light intensity; L represents the effective optical path; σ(λ) represents the absorption cross section of the gas to be measured; and c represents the concentration of the gas to be measured.

[0041] Considering Rayleigh scattering, Mie scattering and absorption of other gas molecules, expression (1) is corrected to:

[0042]

[0043] Where: λ represents the wavelength of the spectrum; I(λ) represents the outgoing light intensity; I0(λ) represents the incident light intensity; L represents the effective optical path; σ i ′(λ) represents the absorption cross section of the i-th gas to be measured; c i Indicates the concentration of the gas to be measured.

[0044] A reference analysis channel is introduced. There is no gas absorption or the absorption can be ignored within the filter bandwidth of this channel. Then the signal attenuation amplitude caused by external interference at any time is the same as that of the target gas analysis channel. After conversion to absorbance, formula (2) can be corrected as follows:

[0045]

[0046] Where: A represents the total absorbance, I1′(λ) and I1(λ) are the reference signal intensities before and after gas absorption, respectively; Ai is the absorbance of the i-th gas.

[0047] In NDIR multi-component gas analysis, there are n filters used to measure n target gases respectively. The total absorbance in each analysis channel is the superposition of a series of absorbances. Therefore, the n analysis channels can establish an n-dimensional linear regression equation group, as shown in formula (4). By solving the n-dimensional linear regression equation group, the CO2 concentration value C can be obtained. (CO2) The CO2 mass absorbed by plant photosynthesis or emitted by litter decomposition is calculated based on the difference of CO2 concentration measured multiple times and the size of the enclosed space, which are S j and L t1 .

[0048]

[0049] The online gas chromatography analysis equipment adopts a highly sensitive hydrogen flame ionization detector (FID) to measure low concentration CH4, and has the functions of automatic ignition upon power-on, automatic display of flow rates of hydrogen, air, tail blowing, automatic over-temperature protection, etc. It has high sensitivity, simple maintenance, low gas consumption, and gas saving. The FID detector uses nitrogen as carrier gas, hydrogen and air as energy sources, so that the sample components separated by the chromatographic column undergo chemical ionization, and the organic compound C m H n After the following reaction: C m H n →-CH; -CH+O→CHO + +e - ; CHO + +H2O→H3O + +CO, the positive and negative ions generated after ionization form a micro-current under the action of the micro-electric plant formed by the polarization voltage. Within a certain range, the size of the signal is proportional to the mass of the measured component entering the detector per unit time. The electrical signal is recorded to obtain a chromatogram with a peak area proportional to the organic compound. The organic compound is qualitatively and quantitatively analyzed according to the chromatogram of the hydrogen flame ionization detector, thereby obtaining the concentration value C of the measured component CH4 (CH4) The difference of CH4 concentration measured multiple times can be used to obtain the CH4 mass emitted by plant litter according to the size of the enclosed space, that is, L t2 .

[0050] A method for determining the net carbon fixation capacity of plants by an automated system comprises the following steps:

[0051] S100: The temperature sensor 6, the humidity sensor 7 and the pressure sensor 20 monitor the environmental conditions of the working room 3 in the incubator in real time, transmit the signal to the PLC controller 25, and display it on the host computer IPC 26;

[0052] S200: When the temperature or humidity of the inner working room 3 is lower than or higher than the set value, the PLC controller 25 receives the signal of the temperature sensor 6 or the humidity sensor 7, and controls the constant temperature and humidity regulating device to regulate the temperature or humidity of the inner working room 3, so that the temperature or humidity of the inner working room 3 reaches the set value; when the pressure exceeds the set value, the PLC controller 25 controls the air intake device and the exhaust device according to the signal of the pressure sensor 20 until the pressure of the inner working room 3 reaches the set value;

[0053] S300: The vacuum pump 18 is started at a fixed time, and the sample gas is extracted from the exhaust device and enters the gas online continuous automatic monitoring unit to measure the concentration of different gases and transmit the data to the upper computer IPC26;

[0054] S400: When the gas concentration exceeds the set value, the PLC controller 25 controls the air intake device and the exhaust device until the gas concentration in the inner working room 3 returns to the set value, and the gas analyzed by the online continuous automatic monitoring unit re-enters the inner working room 3 through the air intake device to keep the gas composition in the inner working room 3 unchanged.

[0055] S500: The net carbon fixation capacity of plants is the carbon fixation benefit after removing the carbon emissions of plants. After analysis by the online infrared analysis device 22, the CO2 mass absorbed by the net photosynthesis of plants and the CO2 emission of plant litter decomposition can be obtained. After measurement by the online gas chromatography analysis device 24, the CH4 emission of plant litter decomposition can be obtained. The calculation method of the net carbon fixation capacity of plants is:

[0056]

[0057] Where: M represents the net carbon fixation capacity of plants; 12 / 44 represents the coefficient of CO2 conversion to C; S j represents the mass of CO2 absorbed by plants through net photosynthesis in j days; L t1 L represents the CO2 emission from the decomposition of dry matter grown by plants in time j within time t; t2 represents the CH4 emission from the decomposition of dry matter grown by plants in time j during time t; 25 represents the coefficient of conversion of CH4 into CO2 equivalent.

[0058] The following is combined with Figure 1 and 2 The preferred embodiment of the present system is described in detail.

[0059] Embodiment 1:

[0060] A measuring system for studying the net CO2 absorption of plants is provided, and the operation process of the system is described in detail below.

[0061] The carrier gas cylinder 12 is a mixed gas cylinder, and the second gas solenoid valve 23 is always in a closed state. The temperature sensor 6, humidity sensor 7 and pressure sensor 20 monitor the environmental conditions of the working room 3 in the incubator in real time, transmit the signal to the PLC controller 25, and display it on the host computer IPC26. When the temperature or humidity of the inner working room 3 is lower than or higher than the set value, the PLC controller 25 receives the signal from the temperature sensor 6 or humidity sensor 7, and controls the constant temperature and humidity adjustment device to adjust the temperature or humidity of the inner working room 3 so that the temperature or humidity of the inner working room 3 reaches the set value; when the pressure exceeds the set value, the PLC controller 25 controls the switch state of the gas supply and exhaust unit according to the signal of the pressure sensor 20, monitors the gas flow, until the inner working room is 3 reaches the set value; the vacuum pump 18 is turned on at a fixed time, and the sample gas is extracted by the sampling probe 5 and then enters the gas online continuous automatic monitoring unit through the valve conversion of the second electromagnetic three-way valve 19. The sample gas enters the online infrared analysis equipment 22 through the first gas solenoid valve 21 to measure the CO2 and O2 concentrations. At this time, the PLC controller 25 receives the CO2 concentration and O2 concentration signals of the online infrared analysis equipment 22 and transmits the data to the host computer IPC26. However, when the CO2 and O2 concentrations exceed the set value, the PLC controller 25 will control the switch state of the gas supply and exhaust unit and monitor the gas flow until the gas concentration in the inner working room 3 returns to the set value.

[0062] Embodiment 2:

[0063] A measuring system for studying the release of CO2 and CH4 from litter decomposition in an aerobic environment is provided. The operation process of the system is described in detail below.

[0064] The temperature sensor 6, humidity sensor 7 and pressure sensor 20 monitor the environmental conditions of the working room 3 in the incubator in real time, transmit the signal to the PLC controller 25, and display it on the upper computer IPC26. When the temperature or humidity of the inner working room 3 is lower than or higher than the set value, the PLC controller 25 receives the signal of the temperature sensor 6 or the humidity sensor 7, and controls the constant temperature and humidity adjustment device to adjust the temperature or humidity of the inner working room 3 so that the temperature or humidity of the inner working room 3 reaches the set value; when the pressure exceeds the set value, the PLC controller 25 controls the switch state of the gas supply and exhaust unit according to the signal of the pressure sensor 20, monitors the gas flow, until the pressure of the inner working room 3 reaches the set value; the vacuum pump 18 is turned on at a fixed time, and the sampling probe 5 extracts the sample gas and then switches it into the valve of the second electromagnetic three-way valve 19. The gas enters the online continuous automatic monitoring unit, one sample gas enters the online infrared analysis equipment 22 through the first gas solenoid valve 21, and is used to measure the CO2 and O2 concentrations. The other sample gas enters the online gas chromatography analysis equipment through the second gas solenoid valve 23, and is used to measure the CH4 concentration. At this time, the PLC controller 25 receives the signals of CO2 concentration, O2 concentration and CH4 concentration, and transmits the data to the host computer IPC26. However, when the CO2 and O2 concentrations exceed the set values, the PLC controller 25 will control the switch state of the gas supply and exhaust unit and monitor the gas flow until the gas concentration in the inner working room 3 returns to the set value. The gas analyzed by the online continuous automatic monitoring unit re-enters the inner working room 3 through the first electromagnetic three-way valve 10 to keep the gas composition in the inner working room 3 of the incubator unchanged.

[0065] Embodiment 3:

[0066] A measuring system for studying the release of CO2 and CH4 from litter decomposition in an anaerobic environment is provided. The operation process of the system is described in detail below.

[0067] The carrier gas cylinder 12 is a N2 cylinder. At the beginning of the experiment, the air intake device transports N2 into the incubator, and the exhaust device draws air out of the incubator until the incubator is filled with N2 to create an oxygen-free environment; the first electromagnetic three-way valve 10 is closed to cut off the air intake source; the temperature sensor 6, the humidity sensor 7 and the pressure sensor 20 monitor the environmental conditions of the working room 3 in the incubator in real time, transmit the signal to the PLC controller 25, and display it on the upper computer IPC26. When the temperature or humidity in the inner working room 3 is lower than or higher than the set value, the PLC controller 25 receives the signal from the temperature sensor 6 or the humidity sensor 7, and controls the constant temperature and humidity adjustment device to adjust the temperature and humidity of the inner working room 3 so that the temperature and humidity of the inner working room 3 reach the set value; when the pressure exceeds the set value, the PLC controller 25 adjusts the temperature and humidity of the inner working room 3 according to the signal of the pressure sensor 20 The signal controls the switch state of the gas supply and exhaust unit and monitors the gas flow until the pressure in the inner working room 3 reaches the set value; the vacuum pump 18 is turned on at a fixed time, and the sample gas is extracted by the sampling probe 5 and then enters the gas online continuous automatic monitoring unit through the valve conversion of the second electromagnetic three-way valve 19. One path of sample gas is extracted by the sampling probe 5 and then enters the online infrared analysis equipment 22 through the first gas solenoid valve 21 to measure the CO2 concentration. The other path of sample gas enters the online gas chromatography analysis equipment through the second gas solenoid valve 23 to measure the CH4 concentration. At this time, the PLC controller 25 receives the signals of CO2 concentration and CH4 concentration, and transmits the data to the host computer IPC26. The gas analyzed by the online continuous automatic monitoring unit re-enters the inner working room 3 through the first electromagnetic three-way valve 10 to keep the gas composition of the working room 3 in the incubator unchanged.

Claims

1. An automated system for determining net carbon fixation capacity of plants, characterized in that: The invention comprises a plant artificial photosynthesis incubator, a gas supply and exhaust unit and a gas online continuous automatic monitoring unit controlled by an upper computer IPC (26) and a PLC controller (25). The plant artificial photosynthesis incubator comprises an outer shell (1), wherein a sealed inner working chamber (3) is arranged inside the outer shell (1), wherein an LED light source (2), a temperature sensor (6), a humidity sensor (7), a pressure sensor (20) and a constant temperature and humidity regulating device (14) are arranged inside the inner working chamber (3), wherein the temperature sensor (6), the humidity sensor (7) and the pressure sensor (20) transmit the temperature, humidity and pressure signals of the inner working chamber to a PLC controller (25) at any time, and display the signals on a host computer IPC (26). The gas supply and exhaust unit comprises an air intake device and an air exhaust device connected to the inner working chamber (3); The gas online continuous automatic monitoring unit comprises a first gas solenoid valve (21), a second gas solenoid valve (23), an online infrared analysis device (22) and an online gas chromatography analysis device (24); the air inlet ends of the first gas solenoid valve (21) and the second gas solenoid valve (23) are connected to an exhaust device; the exhaust ends are respectively connected to the online infrared analysis device (22) and the online gas chromatography analysis device (24); the online infrared analysis device (22) and the online gas chromatography analysis device (24) are connected to the air inlet device via a pipeline; The air intake device comprises a carrier gas cylinder (12), an air intake pump (9), a first electromagnetic three-way valve (10), a first gas flow meter (11), and an air intake hole (15) provided on the inner working chamber (3), which are connected in sequence by pipelines. The exhaust device comprises a sampling probe (5), an air extraction hole (16), an air extraction pump (18), a second electromagnetic three-way valve (19) and a second gas flow meter (17); the sampling probe (5) is arranged in the inner working room (3); the air extraction hole (16) is arranged on the working room (3); the sampling probe (5) is connected to the air extraction hole (16); the air extraction hole (16) is connected to the second gas flow meter (17), the air extraction pump (18) and the second electromagnetic three-way valve (19) in sequence; The second electromagnetic three-way valve (19) is connected to the first gas electromagnetic valve (21) and the second gas electromagnetic valve (23).

2. The automated plant net carbon fixation capacity determination system according to claim 1, characterized in that: The online infrared analysis device (22) and the online gas chromatography analysis device (24) are connected to the first electromagnetic three-way valve (10) of the air intake device via pipelines.

3. The automated plant net carbon fixation capacity determination system according to claim 1, characterized in that: The inner working room (3) is provided with a plexiglass window (4).

4. The automated plant net carbon fixation capacity determination system according to claim 1, characterized in that: The LED light source (2) has built-in light-emitting diodes of four wavelength bands: red, white, blue and green, and also includes an ultraviolet lamp.

5. The automated plant net carbon fixation capacity determination system according to claim 1, characterized in that: The constant temperature and humidity regulating device comprises a refrigeration unit, a heating system, a humidification system and a dehumidification system. The constant temperature and humidity regulating device is placed between the outer shell (1) and the inner working room (3) and is in communication with the inner working room (3).

6. A method for measuring the automatic plant net carbon fixation capacity measuring system as claimed in claim 1, 2, 3, 4 or 5, characterized in that: The following steps are included: S100: The temperature sensor (6), humidity sensor (7) and pressure sensor (20) monitor the environmental conditions of the working room (3) in the incubator in real time, transmit the signal to the PLC controller (25), and display it on the host computer IPC (26); S200: When the temperature or humidity of the inner working room (3) is lower than or higher than a set value, the PLC controller (25) receives a signal from the temperature sensor (6) or the humidity sensor (7), and controls the constant temperature and humidity regulating device to regulate the temperature or humidity of the inner working room (3) so that the temperature or humidity of the inner working room (3) reaches the set value; when the pressure exceeds the set value, the PLC controller (25) controls the air intake device and the exhaust device according to the signal from the pressure sensor (20) until the pressure of the inner working room (3) reaches the set value; S300: start the vacuum pump (18) at a fixed time, extract the sample gas from the exhaust device and enter the gas online continuous automatic monitoring unit to measure the concentration of different gases, and transmit the data to the upper computer IPC (26); S400: When the gas concentration exceeds the set value, the PLC controller (25) controls the air intake device and the exhaust device until the gas concentration in the inner working chamber (3) returns to the set value, and the gas analyzed by the online continuous automatic monitoring unit re-enters the inner working chamber (3) through the air intake device to keep the gas composition in the inner working chamber (3) unchanged; S500: Numerical calculation of plant net carbon fixation capacity: After analysis by the online infrared analysis device (22), the mass of CO2 absorbed by the net photosynthesis of the plant and the CO2 emission from the decomposition of the plant litter can be obtained; after measurement by the online gas chromatography analysis device (24), the CH4 emission from the decomposition of the plant litter can be obtained respectively; the calculation method of the net carbon fixation capacity of the plant is: Where: M represents the net carbon fixation capacity of plants; 12 / 44 represents the coefficient of CO2 conversion to C; S j represents the mass of CO2 absorbed by plants through net photosynthesis in j days; L tj1 L represents the CO2 emission from the decomposition of dry matter grown by plants in time j within time t; tj2 represents the CH4 emission from the decomposition of dry matter grown by plants in time j during time t; 25 represents the coefficient of conversion of CH4 into CO2 equivalent.

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