Multi-pollutant geogas exchange flux sampling device and method

Abstract

The invention provides a multi-pollutant geogas exchange flux sampling device and method, and relates to the technical field of atmospheric pollutant detection. The volatile organic compound sampling system comprises an upper gas sampling pipe, a middle gas sampling pipe, a lower gas sampling pipe, a first busbar, a first mass flow controller, a first gas pump and a first data collector, and the first data collector controls a first electromagnetic valve to be opened to collect volatile organic compound gaseous samples according to the wind speed data; the inorganic gas-particulate matter series sampling system comprises a particle cutter, an upper particle sampling pipe, a middle particle sampling pipe, a lower particle sampling pipe, a second busbar, a second mass flow controller, a second air pump and a second data collector, and the upper particle sampling pipe, the middle particle sampling pipe and the lower particle sampling pipe respectively comprise a gas corrosion device; the second data collector controls a second electromagnetic valve to be opened to collect inorganic gas and atmospheric particulates according to the wind speed data. The device has the beneficial effects that collection and flux detection of various atmospheric pollutants are realized, and gaseous and particulate samples can be synchronously and accurately collected.

Description

Technical Field

[0001] The present invention relates to the technical field of atmospheric pollutant detection, and particularly to a multi-pollutant ground-air exchange flux sampling device and method. Background Art

[0002] The atmosphere has a complex and diverse composition, including not only trace gases such as methane (CH4), ammonia (NH3), sulfur dioxide (SO2), ozone (O3), nitrogen oxides (NO x ) and volatile organic compounds (VOCs), but also particulate matter containing various inorganic salts, metals, and organic substances.

[0003] Flux observation is an important means to study the exchange of matter and energy between the atmosphere and the earth's surface. The method for measuring fluxes at the ecosystem and site investigation scales is the micrometeorological method. Micrometeorological methods mainly include the eddy covariance method (Eddy Covariance, EC) and its derivative methods. The eddy correlation method is the most widely used and mature micrometeorological method at present. The basic principle of this method is that the flux of gas in the vertical direction can be expressed as the covariance of the vertical wind speed fluctuation and the concentration fluctuation. Among them, the vertical wind speed fluctuation can be measured at high frequency by a three-dimensional ultrasonic anemometer (usually 10 - 20 Hz); the concentration fluctuation can be measured synchronously at high frequency by an open-path or closed-path gas analyzer (i.e., 10 - 20 Hz).

[0004] However, the current eddy covariance method measurement devices on the market have the following problems: (1) For each measurement gas, a separate high-frequency concentration measurement instrument needs to be configured, and these instruments are either expensive or not technically capable of high-frequency measurement at present. (2) Currently, there are only eddy covariance method measurement instruments for greenhouse gases such as carbon dioxide, water vapor, methane, and nitrous oxide on the market, and there is no mature product for measuring atmospheric pollutant fluxes. Summary of the Invention

[0005] In view of this, in order to solve the above problems existing in the eddy covariance method measurement device, an embodiment of the present invention provides a multi-pollutant ground-air exchange flux sampling device and method.

[0006] An embodiment of the present invention provides a multi-pollutant ground-air exchange flux sampling device, including:

[0007] A three-dimensional anemometer for high-frequency acquisition of wind speed data;

[0008] Volatile organic compound sampling system, which includes an upper intake pipe, a lower intake pipe, a middle intake pipe, a plurality of gas sampling pipes, a first manifold, a first mass flow controller, a first air pump, and a first data collector. Each of the gas sampling pipes is closed at both ends and is internally provided with a polymer adsorbent. Among them, the upper ends of some of the gas sampling pipes are respectively detachably connected to the upper intake pipe to form upper gas sampling pipes, the upper ends of some of the gas sampling pipes are respectively detachably connected to the lower intake pipe to form lower gas sampling pipes, and the upper ends of the other gas sampling pipes are respectively detachably connected to the middle intake pipe to form middle gas sampling pipes. The lower end of each gas sampling pipe is detachably connected to a first solenoid valve, and each of the first solenoid valves is connected to the first manifold. The first manifold is connected to the first mass flow controller, the first mass flow controller is connected to the first air pump, and the first data collector is connected to the three-dimensional anemometer, the first mass flow controller, the first air pump, and each of the first solenoid valves to control the opening of one of the first solenoid valves according to the wind speed data, so that the gas sampling pipe where the first solenoid valve is located collects volatile organic compound gaseous samples;

[0009] And an inorganic gas - particulate matter series sampling system, which includes a particle cutter, an upper intake channel, a middle intake channel, a lower intake channel, three particle sampling pipes, a second manifold, a second mass flow controller, a second air pump, and a second data collector. The particle cutter is respectively connected to the upper intake channel, the middle intake channel, and the lower intake channel. The upper end of one of the particle sampling pipes is detachably connected to the upper intake channel to form an upper particle sampling pipe, the upper end of one of the particle sampling pipes is detachably connected to the middle intake channel to form a middle particle sampling pipe, and the upper end of the other particle sampling pipe is detachably connected to the lower intake channel to form a lower particle sampling pipe. Each particle sampling pipe is internally provided with a gas dissolver and is provided with a filter membrane for collecting particulate matter in the air flow at the lower end. The lower end of each particle sampling pipe is detachably connected to a second solenoid valve, and each of the second solenoid valves is connected to the second manifold. The second manifold is connected to the second mass flow controller, the second mass flow controller is connected to the second air pump, and the second data collector is connected to the three-dimensional anemometer, the second mass flow controller, the second air pump, and each of the second solenoid valves to control the opening of one of the second solenoid valves according to the wind speed data, so that the particle sampling pipe where the second solenoid valve is located collects inorganic gases and atmospheric particulate matter.

[0010] Further, the number of the upper gas sampling pipes of the volatile organic compound sampling system is the same as the number of the lower gas sampling pipes.

[0011] Further, the volatile organic compound sampling system further includes a bypass pipeline, and the bypass pipeline is connected to the first manifold.

[0012] Further, the polymer adsorbent is Tenax-TA polymer adsorbent; and ozone removal devices are provided on both the upper air inlet pipe and the lower air inlet pipe.

[0013] Further, a first filtering device is provided between the first manifold and the first mass flow controller.

[0014] Further, a second filtering device is provided between the second manifold and the second mass flow controller.

[0015] Further, it includes a wireless communication module, which connects an external computer to the first data collector and the second data collector.

[0016] In addition, an embodiment of the present invention also provides a multi-pollutant ground-air exchange flux sampling method, which uses the above multi-pollutant ground-air exchange flux sampling device and includes the following steps:

[0017] S1. Determine that the residence time of the air flow in the common pipeline is t1 according to the gas flow rate, the volume of the common pipeline of the volatile organic compound sampling system, and the volume of the common pipeline of the inorganic gas-particulate matter series sampling system, and set the required shortest sampling time as t2;

[0018] S2. Control the pre-operation time t3 of the three-dimensional anemometer, and obtain the initial wind speed average value and the standard deviation σ; and during the subsequent operation of the three-dimensional anemometer, update the wind speed average value and the standard deviation σ every t3 time;

[0019] S3. Control the three-dimensional anemometer to detect the wind speed data every t2 time to obtain the wind speed average value w of the current time period, and compare it with the wind speed average value of the previous t3 time of the current time period and the standard deviation σ, so as to judge the opening states of the first solenoid valve and the second solenoid valve after t1 time:

[0020] When is satisfied, start the first solenoid valve on the upper gas sampling tube and the second solenoid valve on the upper particle sampling tube;

[0021] When is satisfied, start the first solenoid valve on the lower gas sampling tube and the second solenoid valve on the lower particle sampling tube;

[0022] When is satisfied, start the first solenoid valve on the middle gas sampling tube and the second solenoid valve on the middle particle sampling tube;

[0023] S4. Disassemble the gaseous and particulate samples in the gas sampling tube and the particle sampling tube after sampling for analysis and detection:

[0024] Further, in step S3, the upper gas sampling tubes and the lower gas sampling tubes are combined one by one to form multiple groups of sampling tube groups, and each group of sampling tubes samples at a target time in sequence.

[0025] Further, the sampling periods of the volatile organic compound sampling system and the inorganic gas - particulate matter tandem sampling system are the same or different, and the numbers of the gas sampling tubes and the particulate sampling tubes can be adjusted according to actual measurement requirements.

[0026] The beneficial effects brought by the technical solutions provided in the embodiments of the present invention are as follows:

[0027] 1. A multi - pollutant ground - air exchange flux sampling device of the present invention uses a three - dimensional anemometer to monitor and collect the wind speed at high frequency. According to the wind speed, the first solenoid valve and the second solenoid valve are controlled to open. When the vertical wind speed is upward, the samples are collected into the upper gas sampling tubes and the upper particulate sampling tubes. When the vertical wind speed is downward, the samples are collected into the lower gas sampling tubes and the lower particulate sampling tubes. When the vertical wind speed does not exceed the set threshold, the samples are collected into the middle gas sampling tubes and the middle particulate sampling tubes. The gas sampling tubes and the particulate sampling tubes after sampling can be detached for subsequent off - line chemical component measurement. In this way, the gaseous and particulate samples of atmospheric pollutants can be collected according to the relaxation eddy accumulation method, and the collection and flux measurement of multiple atmospheric pollutants can be realized. Compared with the eddy covariance method and other relaxation eddy accumulation methods that only achieve the flux measurement of a few greenhouse gases and pollutants, this method combines on - line sampling and off - line chemical analysis and can realize the synchronous measurement of the fluxes of more than 90% of atmospheric pollution components.

[0028] 2. A multi - pollutant ground - air exchange flux sampling method of the present invention, according to the preset rules, in the case of a time delay in the transmission of the air flow from near the three - dimensional anemometer to the sampling medium, controls the opening of the first solenoid valve and the second solenoid valve according to the real - time wind speed information, so that there is a time difference between the wind speed measurement and the opening and closing of the solenoid valves, accurately realizing high - frequency synchronous sampling, ensuring that the pollutants are collected into the corresponding gas sampling tubes and particulate sampling tubes, and ensuring that the gaseous and particulate samples can be synchronously and accurately collected. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of a multi - pollutant ground - air exchange flux sampling device of the present invention;

[0030] Figure 2 is a schematic diagram of a volatile organic compound sampling system;

[0031] Figure 3 is a schematic diagram of an inorganic gas - particulate matter tandem sampling system.

[0032] In the figure: 1. Three-dimensional anemometer; 2. First signal adapter; 3. Transformer; 4. Power supply; 5. First data collector; 6. First relay; 7. First wiring board; 8. Meteorological instrument; 9. External computer; 10. Volatile organic compound sampling system; 11. First mass flow controller; 12. First air pump; 13. Second signal adapter; 14. Second data collector; 15. Second relay; 16. Second wiring board; 17. Inorganic gas - particulate matter series sampling system; 18. Second mass flow controller; 19. Second air pump; 20. Thermocouple temperature sensor; 21. Wireless communication module; 22. Upper intake pipe; 23. Lower intake pipe; 24. Middle intake pipe; 25. Bypass pipe; 26. Upper gas sampling pipe; 27. Lower gas sampling pipe; 28. Middle gas sampling pipe; 29. First solenoid valve; 30. First manifold; 31. First filter device; 32. Ozone removal device; 33. Four-way joint; 34. Three-way joint; 35. Particle cutter; 36. Upper intake channel; 37. Middle intake channel; 38. Lower intake channel; 39. Upper particle sampling pipe; 40. Middle particle sampling pipe; 41. Lower particle sampling pipe; 42. Filter membrane; 43. Second solenoid valve; 44. Second manifold; 45. Second filter device. Detailed implementation manners

[0033] To make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings. The following introduces a relatively optimal one among multiple possible embodiments of the present invention, aiming to provide a basic understanding of the present invention, but not aiming to identify the key or decisive elements of the present invention or limit the scope to be protected.

[0034] In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0035] For technologies, methods and devices known to those of ordinary skill in the relevant art, they may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the specification.

[0036] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings. At the same time, it should be understood that for the sake of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships.

[0037] It should be noted that, unless otherwise clearly specified and defined, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0038] Please refer to Figure 1 , an embodiment of the present invention provides a multi-pollutant ground-air exchange flux sampling device, which mainly includes a three-dimensional anemometer 1, a volatile organic compound sampling system 10, and an inorganic gas-particulate matter series sampling system 17 integrated together.

[0039] The three-dimensional anemometer 1 is used to monitor and collect high-frequency wind speed data. In this embodiment, the three-dimensional anemometer 1 selects a CSAT3B three-dimensional ultrasonic anemometer, which can accurately detect the current wind speed data.

[0040] Please refer to Figure 2 , the volatile organic compound sampling system 10 includes an upper intake pipe 22, a lower intake pipe 23, a middle intake pipe 24, a plurality of gas sampling tubes, a first manifold 30, a first mass flow controller 11, a first air pump 12, and a first data collector 5.

[0041] Both ends of each gas sampling tube are closed, and a polymer adsorbent is provided inside. A variety of polymer adsorbents can be selected to fill the gas sampling tube according to needs, and the polymer adsorbent is selectively selected according to the target organic compound to be adsorbed. In this embodiment, the polymer adsorbent is a Tenax-TA polymer adsorbent, which can adsorb organic compounds in the atmosphere.

[0042] Among the gas sampling tubes, some of the gas sampling tubes are detachably connected to the upper intake pipe 22 at the upper ends to form upper gas sampling tubes 26, some of the gas sampling tubes are detachably connected to the lower intake pipe 23 at the upper ends to form lower gas sampling tubes 27, and the upper ends of the other gas sampling tubes are respectively detachably connected to the middle intake pipe 24 to form middle gas sampling tubes 28. The lower end of each gas sampling tube is detachably connected to a first solenoid valve 29, each first solenoid valve 29 is connected to the first manifold 30, the first manifold 30 is connected to the first mass flow controller 11, and the first mass flow controller 11 is connected to the first air pump 12. Among them, the atmospheric airflow will selectively enter the upper intake pipe 22, the lower intake pipe 23, and the middle intake pipe 24 according to the change of the vertical wind speed, and form an air current under the pumping action of the first air pump 12.

[0043] The first data collector 5 is connected to the three-dimensional anemometer 1 and the first relay 6 to control the opening of a first solenoid valve 29 according to wind speed data, so that the gas sampling tube where the first solenoid valve 29 is located collects gaseous samples of volatile organic compounds. In this embodiment, the first data collector 5 is a CR6 data collector. As the control center of the volatile organic compound sampling system 10, the three-dimensional anemometer 1 is connected to the first data collector 5 through a first signal adapter 2, and the first data collector 5 is connected to the first wiring board 7 through the first relay 6. The wind speed signal collected by the three-dimensional anemometer 1 is transmitted to the first signal adapter 2, which converts the RS485 signal into an RS232 signal and transmits it to the first data collector 5. After the wind speed signal collected by the first data collector 5 is calculated and judged, an instruction is transmitted to the first relay 6. The first relay 6 transmits the wind speed signal to the first wiring board 7, and the first wiring board 7 leads out the wind speed signal to the first solenoid valve 29 in the volatile organic compound sampling system 10. The first data collector 5 controls the opening of the first solenoid valve 29. For example, when the vertical wind speed is upward, the first solenoid valve 29 on an upper gas sampling tube 26 is controlled to open, so that the sample is collected into the upper gas sampling tube 26 when the vertical wind speed is upward; when the vertical wind speed is downward, the first solenoid valve 29 on a lower gas sampling tube 27 is controlled to open, so that the sample is collected into the lower gas sampling tube 27 when the vertical wind speed is downward; when the vertical wind speed does not exceed the set threshold, the first solenoid valve 29 on a middle gas sampling tube 28 is controlled to open, so that the sample is collected into the middle gas sampling tube 28.

[0044] It should be noted that the number of the gas sampling tubes can be flexibly set according to actual sampling needs. The number of the upper gas sampling tubes 26 and the number of the lower gas sampling tubes 27 are generally set to be relatively large, and only one middle gas sampling tube 28 is provided. After one upper gas sampling tube 26 has completed sampling, it can be disassembled, and the first data collector 5 controls the first solenoid valve 29 on another upper gas sampling tube 26 to open, and switches to another upper gas sampling tube 26 for sampling. Similarly, after one lower gas sampling tube 27 has completed sampling, it can be disassembled, and the first data collector 7 controls the first solenoid valve 29 on another lower gas sampling tube 27 to open, and switches to another lower gas sampling tube 27 for sampling.

[0045] Moreover, considering the actual situation of collecting samples by the relaxation vorticity accumulation method, the number of the upper gas sampling tubes 26 is the same as that of the lower gas sampling tubes 27. The upper gas sampling tubes 26 and the lower gas sampling tubes 27 are combined one by one to form multiple groups of sampling tube groups, and each group of sampling tubes samples at the target time in turn. In this embodiment, the number of the upper gas sampling tubes 26 and the number of the lower gas sampling tubes 27 are both four. The upper air inlet pipe 22 is connected to the two upper gas sampling tubes 26 and a tee 34 through a four-way 33, and the tee 34 is connected to the other two upper gas sampling tubes 26. Each group of sampling tubes switches to another group of sampling tubes after sampling for 1 hour.

[0046] In this embodiment, the volatile organic compound sampling system 10 further includes a bypass pipeline 25. The bypass pipeline 25 is connected to the first manifold 30, and a first solenoid valve 29 is also provided between the bypass pipeline 25 and the first manifold 30. When no sampling is carried out, the first solenoid valve 29 on the bypass pipeline 25 is opened to avoid the negative pressure in the pipeline caused by the operation of the first air pump 12.

[0047] In some embodiments, ozone removal devices 32 are provided on both the upper air inlet pipe 22 and the lower air inlet pipe 23. The air flows entering the upper air inlet pipe 22 and the lower air inlet pipe 23 will pass through the ozone removal devices 32 to remove the interference of ozone on sampling.

[0048] In some embodiments, a first filtering device 31 is provided between the first manifold 30 and the first mass flow controller 11. The air flow flowing out of the first manifold 30 enters the first filtering device 31 to remove impurities in the air flow. The first mass flow controller 11 is used to control and monitor the sampling flow rate of the volatile organic compound sampling system 10, and can adjust the sampling flow rate according to the first air pump 12.

[0049] Please refer to Figure 3 , the inorganic gas - particulate matter tandem sampling system 17 includes a particle cutter 35, an upper air inlet channel 36, a middle air inlet channel 37, a lower air inlet channel 38, three particle sampling tubes, a second manifold 44, a second mass flow controller 18, a second air pump 19 and a second data collector 14.

[0050] The particle cutter 35 is respectively connected to the upper air inlet channel 36, the middle air inlet channel 37 and the lower air inlet channel 38. The particle cutter 35 is used to separate the particulate matter in the air with a diameter less than or equal to 2.5 micrometers, and the separated PM 2.5 particles enter the upper air inlet channel 36, the middle air inlet channel 37 or the lower air inlet channel 38 selectively along with the air flow.

[0051] The three particle sampling tubes are arranged side by side. The upper end of one particle sampling tube is detachably connected to the upper air inlet channel 36 to form an upper particle sampling tube 39. The upper end of one particle sampling tube is detachably connected to the middle air inlet channel 37 to form a middle particle sampling tube 40. The upper end of the other particle sampling tube is detachably connected to the lower air inlet channel 38 to form a lower particle sampling tube 41. A gas dissolver is provided in each particle sampling tube, and a filter membrane 42 for collecting particulate matter in the air flow is provided at the lower end. The gas dissolver can selectively collect gas pollutants according to the sampling purpose. For example, the gas dissolver can be coated with an acidic or alkaline liquid film as needed to selectively absorb various inorganic gases such as sulfur dioxide, nitrogen oxides, and ammonia. The filter membrane 42 is used to collect particulate matter in the air flow. The particulate matter collected by the filter membrane 42 can also be used to measure inorganic salts, metal elements, and organic particulate matter in atmospheric particulate matter according to subsequent laboratory off-line analysis methods. The lower end of each particle sampling tube is detachably connected to a second solenoid valve 43. Each of the second solenoid valves 43 is connected to the second manifold 44. The second manifold 44 is connected to the second mass flow controller 18. The second mass flow controller 18 is connected to the second air pump 19.

[0052] The second data collector 14 is connected to the three-dimensional anemometer 1, the second mass flow controller 18, the second air pump 19, and each of the second solenoid valves 43. Specifically, the second data collector 14 is a CR1000X data collector. As the control center of the inorganic gas - particulate matter tandem sampling system 17, the three-dimensional anemometer 1 is connected to the second signal adapter 13. The second signal adapter 13 is connected to the second data collector 14. The second data collector 14 is connected to the second relay 15. The second relay 15 is connected to the second terminal block 16. The wind speed signal collected by the three-dimensional anemometer 1 is transmitted to the second signal adapter 13, which converts the RS485 signal into an RS232 signal and transmits it to the second data collector 14. After calculation and judgment, the instruction is then transmitted to the second relay 15. The second relay 15 transmits the signal to the second terminal block 16. The second terminal block 16 leads out the wind speed signal to the second solenoid valve 43 in the inorganic gas - particulate matter tandem sampling system 17. The second data collector 14 controls the opening of the second solenoid valve 43. For example, when the vertical wind speed is upward, it controls the second solenoid valve 43 on the upper particle sampling tube 39 to open, so that the sample is collected into the upper particle sampling tube 39 when the vertical wind speed is upward; when the vertical wind speed is downward, it controls the second solenoid valve 43 on the lower particle sampling tube 41 to open, so that the sample is collected into the lower particle sampling tube 41 when the vertical wind speed is downward; when the vertical wind speed does not exceed the set threshold, it controls the second solenoid valve 43 on the middle particle sampling tube 40 to open, so that the sample is collected into the middle particle sampling tube 40.

[0053] In some embodiments, a second filtering device 45 is provided between the second bus bar 44 and the second mass flow controller 18. The air flow flowing out of the second bus bar 44 enters the second filtering device 45 to remove impurities in the air flow. The second mass flow controller 18 is used to control and monitor the sampling flow rate of the inorganic gas - particulate matter tandem sampling system 17, and can adjust the sampling flow rate according to the second air pump 19.

[0054] In this embodiment, a multi - pollutant ground - air exchange flux sampling device of the present invention further includes a wireless communication module 21. The external computer 9 is respectively connected to the first data collector 5 and the second data collector 14 by connecting the wireless communication module 21, so as to remotely view and control the operating states and collected data of the volatile organic compound sampling system 10 and the inorganic gas - particulate matter tandem sampling system 17.

[0055] In this embodiment, a multi - pollutant ground - air exchange flux sampling device of the present invention further includes a power supply 4, a thermocouple temperature sensor 20, and a meteorological instrument 8. The power supply 4 is connected to the three - dimensional anemometer 1, the first data collector 5, and the second data collector 14 through a transformer 3. A wiring board 7 is introduced from the first data collector 5 to supply power to the meteorological instrument 8, the first mass flow controller 11, and the first air pump 12; a wiring board 16 is introduced from the second data collector 14 to supply power to the second mass flow controller 18 and the second air pump 19; the thermocouple temperature sensor 20 is connected to the second data collector 14 to provide atmospheric temperature data.

[0056] In addition, an embodiment of the present invention further provides a multi - pollutant ground - air exchange flux sampling method, which uses the above - mentioned multi - pollutant ground - air exchange flux sampling device and includes the following steps:

[0057] S1. According to the gas flow rate, the common pipeline volume of the volatile organic compound sampling system, and the common pipeline volume of the inorganic gas - particulate matter tandem sampling system, determine that the residence time of the air flow in the common pipeline is t1, and set the required shortest sampling time as t2;

[0058] S2. Control the pre - operation time t3 of the three - dimensional anemometer 1 to obtain the initial wind speed average value and standard deviation σ; and during the subsequent operation of the three - dimensional anemometer, update the wind speed average value and standard deviation σ every t3 time. In this embodiment, the pre - operation time t3 is 3 minutes, and during the subsequent operation of the three - dimensional anemometer, update the wind speed average value and standard deviation σ every 3 minutes. The pre - operation time can be flexibly set according to the actual situation.

[0059] S3. Control the three-dimensional anemometer to detect wind speed data every t2 time to obtain the average wind speed w in the current time period, and compare it with the average wind speed standard deviation σ in the previous t3 time of the current time period. Here, compare it with the average wind speed standard deviation σ in the previous 3 minutes of the current time period, so as to judge the opening states of the first solenoid valve and the second solenoid valve after t1 time:

[0060] When , start the first solenoid valve 29 on the upper gas sampling tube 26 and the second solenoid valve 43 on the upper particle sampling tube 39;

[0061] When , start the first solenoid valve 29 on the lower gas sampling tube 27 and the second solenoid valve 43 on the lower particle sampling tube 41;

[0062] When , start the first solenoid valve 29 on the middle gas sampling tube 28 and the second solenoid valve 43 on the middle particle sampling tube 41;

[0063] In the above formula, 0.6 is a coefficient, which can be adjusted according to actual experience or specific sampling environment. In this method, the wind speed measurement and the opening and closing of the first solenoid valve 29 and the second solenoid valve 43 maintain a time difference of t1, so as to ensure that high-frequency synchronous sampling can still be accurately achieved even when there is a time delay in the transmission of the air flow from near the anemometer to the sampling medium.

[0064] S4. Disassemble the gaseous and particulate samples in the gas sampling tube and the particle sampling tube after sampling for analysis and detection.

[0065] And in the step S3, the upper gas sampling tube 26 and the lower gas sampling tube 27 are combined one by one to form multiple groups of sampling tube groups, and each group of sampling tubes sequentially samples at the target time.

[0066] As Figure 2 shown, number the gas sampling tubes from left to right as 1-9. Among them, gas sampling tubes 1-4 are the upper gas sampling tubes 26, gas sampling tube 5 is the middle gas sampling tube 28, and gas sampling tubes 6-9 are the lower gas sampling tubes 27. After the system runs, the sampling is carried out in the following order:

[0067] In the first hour, gas sampling tubes 1 and 6 are sampled;

[0068] In the second hour, gas sampling tubes 2 and 7 are sampled;

[0069] In the third hour, gas sampling tubes 3 and 8 are sampled;

[0070] In the fourth hour, gas sampling tubes 4 and 9 are sampled.

[0071] Meanwhile, as Figure 3 shown, the inorganic gas - particulate matter series sampling system 17 has a set of sampling tube groups including an upper particulate sampling tube 39, a middle particulate sampling tube 40, and a lower particulate sampling tube 41, and continuously samples for 4 hours.

[0072] After 4 hours, the system stops running. At this time, the gas sampling tube can be manually replaced. The gas sampling tube that has completed sampling is saved and can be sent to the laboratory for analysis. In this way, the function of automatically switching each group of sampling tubes is realized to reduce the need for frequent replacement of sampling tubes and simplify on - site operations.

[0073] Both the volatile organic compound sampling system and the inorganic gas - particulate matter series sampling system have a sampling cycle of 4 hours. Also, according to actual needs, the sampling cycle can be modified, and the number of tube groups can be increased or decreased.

[0074] In this article, the front, back, upper, lower and other orientation words are defined based on the positions of the components in the drawings and the positions of the components relative to each other, just for the sake of clarity and convenience in expressing the technical solution. It should be understood that they are relative concepts and can change accordingly according to different usage and placement methods. The use of the orientation words should not limit the scope of protection requested in this application.

[0075] Without conflict, the above - mentioned embodiments and the features in the embodiments in this article can be combined with each other. The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-pollutant ground-air exchange flux sampling device, characterized in that, Comprising: A three-dimensional anemometer for high-frequency acquisition of wind speed data; A volatile organic compound sampling system, which includes an upper intake pipe, a lower intake pipe, a middle intake pipe, a plurality of gas sampling pipes, a first manifold, a first mass flow controller, a first air pump, and a first data collector. Both ends of each of the gas sampling pipes are closed, and a polymer adsorbent is provided inside. Among them, the upper ends of some of the gas sampling pipes are respectively detachably connected to the upper intake pipe to form upper gas sampling pipes, the upper ends of some of the gas sampling pipes are respectively detachably connected to the lower intake pipe to form lower gas sampling pipes, and the upper ends of the other gas sampling pipes are respectively detachably connected to the middle intake pipe to form middle gas sampling pipes. The lower end of each of the gas sampling pipes is detachably connected to a first solenoid valve, each of the first solenoid valves is connected to the first manifold, the first manifold is connected to the first mass flow controller, the first mass flow controller is connected to the first air pump, and the first data collector is connected to the three-dimensional anemometer, the first mass flow controller, the first air pump, and each of the first solenoid valves to control the opening of one of the first solenoid valves according to the wind speed data, so that the gas sampling pipe where the first solenoid valve is located collects gaseous samples of volatile organic compounds; And an inorganic gas - particulate matter series sampling system, which includes a particle cutter, an upper intake channel, a middle intake channel, a lower intake channel, three particle sampling pipes, a second manifold, a second mass flow controller, a second air pump, and a second data collector. The particle cutter is respectively connected to the upper intake channel, the middle intake channel, and the lower intake channel. The upper end of one of the particle sampling pipes is detachably connected to the upper intake channel to form an upper particle sampling pipe, the upper end of one of the particle sampling pipes is detachably connected to the middle intake channel to form a middle particle sampling pipe, and the upper end of the other particle sampling pipe is detachably connected to the lower intake channel to form a lower particle sampling pipe. A gas dissolver is provided inside each of the particle sampling pipes, and a filter membrane for collecting particulate matter in the air flow is provided at the lower end. The lower end of each of the particle sampling pipes is detachably connected to a second solenoid valve, each of the second solenoid valves is connected to the second manifold, the second manifold is connected to the second mass flow controller, the second mass flow controller is connected to the second air pump, and the second data collector is connected to the three-dimensional anemometer, the second mass flow controller, the second air pump, and each of the second solenoid valves to control the opening of one of the second solenoid valves according to the wind speed data, so that the particle sampling pipe where the second solenoid valve is located collects inorganic gases and atmospheric particulate matter.

2. The multi-pollutant ground-air exchange flux sampling device according to claim 1, wherein: The number of the upper gas sampling pipes is the same as that of the lower gas sampling pipes.

3. The multi-pollutant ground-air exchange flux sampling device according to claim 1, characterized in that: The volatile organic compound sampling system further includes a bypass pipeline, and the bypass pipeline is connected to the first manifold.

4. A multi-pollutant ground-air exchange flux sampling device according to claim 1, characterized in that: The polymer adsorbent is Tenax-TA polymer adsorbent; and ozone removal devices are provided on both the upper intake pipe and the lower intake pipe.

5. The multi-pollutant ground-air exchange flux sampling device according to claim 1, characterized in that: A first filtering device is provided between the first manifold and the first mass flow controller.

6. The multi-pollutant ground-air exchange flux sampling device according to claim 1, characterized in that: A second filtering device is provided between the second manifold and the second mass flow controller.

7. The multi-pollutant ground-air exchange flux sampling device according to claim 1, wherein: It further includes a wireless communication module, which is used to connect an external computer to the first data collector and the second data collector.

8. A multi-pollutant ground-air exchange flux sampling method, characterized in that: Using a multi-pollutant soil-air exchange flux sampling device according to any one of claims 1-7, and comprising the following steps: S1. Determine that the residence time of the air flow in the common pipeline is t1 according to the gas flow rate, the volume of the common pipeline of the volatile organic compound sampling system, and the volume of the common pipeline of the inorganic gas-particulate matter tandem sampling system, and set the required shortest sampling time as t2; S2. Control the pre - operation time t3 of the three - dimensional anemometer, and obtain the initial average wind speed and the standard deviation σ; and during the subsequent operation of the three - dimensional anemometer, update the average wind speed every t3 time and the standard deviation σ; S3. Control the three-dimensional anemometer to detect wind speed data every t2 time to obtain the average wind speed w in the current time period, and compare it with the standard deviation σ of the average wind speed in the previous t3 time of the current time period, so as to judge the opening states of the first solenoid valve and the second solenoid valve after t1 time: The standard deviation σ is compared to judge the opening states of the first solenoid valve and the second solenoid valve after t1 time: When the first solenoid valve on the upper gas sampling tube and the second solenoid valve on the upper particle sampling tube are activated; When is satisfied, activate the first solenoid valve on the gas sampling tube and the second solenoid valve on the lower particle sampling tube; When the first solenoid valve on a gas sampling tube and the second solenoid valve on a medium particle sampling tube are activated; S4. Disassemble the gaseous and particulate samples in the gas sampling tube and the particulate sampling tube after sampling for analysis and detection.

9. The multi-pollutant ground-air exchange flux sampling method according to claim 8, wherein: In step S3, the upper gas sampling tube and the lower gas sampling tube are combined one by one to form multiple groups of sampling tube groups, and each group of sampling tubes is sampled for the target time in sequence.

10. A method for sampling multi-pollutant ground-air exchange fluxes as described in claim 8, characterized in that: The sampling periods of the volatile organic compound sampling system and the inorganic gas-particulate matter tandem sampling system are the same or different, and the numbers of the gas sampling tubes and the particulate sampling tubes are adjusted according to actual measurement needs.

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