Buoyancy tank for continuously and automatically observing carbon emission flux of lake

Abstract

The utility model discloses a buoyancy tank for continuously and automatically observing carbon emission flux of a lake, which is used for continuously and automatically observing methane and carbon dioxide emission flux of a water-gas interface of the lake. Comprising a floating body, an airtight floating box and a control box which are combined from bottom to top, the airtight floating box is of a cylindrical hollow structure with the bottomless lower end and the closed top end, an air pump used for air replacement is arranged at the top, and an Arduino micro control computer, a 4G data transmission module and a lithium battery used for power supply are arranged in the control box; a circuit board, a methane sensor, a carbon dioxide sensor, a temperature sensor, a humidity sensor and an air pressure sensor are arranged in the airtight buoyancy tank; air in the airtight buoyancy tank is replaced according to time intervals, the sensors continuously measure data according to the time intervals in the interval time periods and send the data back to the data processing center, and the data processing center calculates the emission flux of methane and carbon dioxide; the device is simple in structure, easy and convenient to operate, low in cost and good in application effect.

Description

Technical Field

[0001] The utility model belongs to the technical field of lake carbon emission observation, and specifically relates to a floating box for continuous and automatic observation of lake carbon emission flux, which can be used for continuous and automatic observation of methane and carbon dioxide emission fluxes at the water-air interface of a lake. Background Art

[0002] Inland water bodies, such as lakes and reservoirs, are major sources of methane and carbon dioxide emissions. Annual methane emissions can account for up to half or more of global natural sources. Therefore, accurately measuring the scale of methane and carbon dioxide emissions from water bodies is crucial. Due to the high spatiotemporal heterogeneity of methane and carbon dioxide emissions above water surfaces, real-time monitoring of the emission dynamics of these gases is essential. Since methane is a trace gas (low background concentration, ~2 ppm), high-resolution dynamic observation of methane emission fluxes above water surfaces requires extremely high equipment requirements. Existing technologies typically construct fixed platforms on the surface of lakes and reservoirs and install high-precision gas concentration analyzers and high-resolution meteorological stations. While this allows for dynamic observation of methane and carbon dioxide emissions at the lake water-air interface, such observation equipment currently needs to be imported. This is not only expensive (a single unit can cost over 3 million yuan) but also requires frequent maintenance by professionals (at least monthly), making it impractical for widespread use and limiting the acquisition of carbon emission flux data from lakes and reservoirs. Therefore, the development of a simple, low-cost floating platform for continuous, automated observation of lake carbon emission fluxes is crucial. Utility Model Content

[0003] In order to overcome the problems existing in the prior art, the utility model provides a floating box for continuous and automatic observation of lake carbon emission flux, which can be used for continuous and automatic observation of methane and carbon dioxide emission fluxes at the water-air interface of lakes.

[0004] The technical purpose of the present invention is achieved in this way: the floating box for continuous and automatic observation of lake carbon emission flux includes a float, an airtight float, and a control box; the airtight float is a cylindrical hollow structure with no bottom at the lower end and a closed top end, and the float is a circular ring structure wrapped around and fixed on the outer periphery of the lower end of the airtight float and keeps the lower end of the airtight float open; a counterweight is set at the bottom of the float, and a plurality of solar panels are evenly set on the float; the control box is set on the top surface of the airtight float, and a lithium battery and a circuit-connected Arduino micro-control computer and a 4G data transmission module are set inside the control box; an air pump is set on the top of the airtight float and is connected to the Arduino micro-control computer circuit, the air inlet of the air pump is connected to the inside of the airtight float and the air outlet corresponds to the outside air, and the side of the airtight float is connected to the outside of the airtight float. A pressure-type air intake check valve is provided below the wall; a circuit board is provided on the top surface of the airtight float tank and is connected to the Arduino microcontroller circuit; a methane sensor, a carbon dioxide sensor, a temperature sensor, a humidity sensor, and an air pressure sensor facing downward are fixedly provided on the circuit board; the lithium battery is used to store electrical energy converted by the solar panel and to power the Arduino microcontroller, the 4G data transmission module, the circuit board, and the air pump; the user remotely controls the Arduino microcontroller via the 4G data transmission module to set the time interval for the air pump to perform air replacement and sensor data measurement, and can control the Arduino microcontroller to perform air replacement and data measurement at time intervals; the measured data is transmitted back to the data processing center by the 4G data transmission module.

[0005] The utility model has the following beneficial effects:

[0006] 1. The utility model uses a bottomless airtight float as a flux box. When floating on the water surface, the airtight float is in an airtight state. The methane and carbon dioxide gases dissolved in the water continue to diffuse from the water body and enter the headspace of the airtight float. The sensor continuously measures the gas concentration according to the set time. The methane and carbon dioxide emission flux in the water body can be calculated based on the continuous data. The airtight float maintains the airtight state for a certain period of time and then replaces the internal air to prevent the methane and carbon dioxide concentration from being too high and forming a large deviation from the actual environmental conditions or exceeding the sensor range, resulting in data unusable. After ventilation, the methane and carbon dioxide concentrations in the airtight float are The temperature returns to the ambient air background concentration again, and a new round of flux measurement begins, thereby realizing continuous and automatic observation of methane and carbon dioxide emission fluxes at the water-air interface of the lake; since methane and carbon dioxide are both by-products of biological metabolic activities in water bodies, their emission patterns are regulated by complex environmental factors and show extremely irregular temporal and spatial heterogeneity. For example, it is known that methane and carbon dioxide emissions have significant diurnal and seasonal variations. At the same time, environmental factors (such as waves formed under wind disturbances) will aggravate gas emissions. Therefore, realizing uninterrupted automatic and high-frequency observation of methane and carbon dioxide emission fluxes is crucial to improving the understanding of the carbon cycle mechanism of inland water bodies.

[0007] 2. Since an Arduino microcontroller and a 4G data transmission module are provided, the user can remotely control the Arduino microcontroller through the 4G data transmission module, execute the air replacement time interval and sensor measurement time interval of the airtight float chamber, and execute air replacement and sensor measurement at time intervals, thereby improving the flexibility of the device application.

[0008] 3. The utility model integrates low-cost industrial-grade sensors and can effectively realize in-situ observation of methane and carbon dioxide fluxes. Relatively speaking, the cost of the utility model is less than 1% of imported equipment, and it can meet scientific research and production needs. It plays a vital role in reducing scientific research costs and reducing dependence on expensive imported scientific research equipment in this technology field, and also contributes to the independent development of equipment in key domestic environmental science and technology fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a side sectional schematic diagram of the utility model;

[0010] Figure 2 It is a top view of the utility model;

[0011] In the figure: 1-floating body; 2-airtight float box; 3-control box; 4-circuit board; 5-air pump; 6-pressure-type air inlet check valve; 7-solar panel; 8-Arduino microcontroller; 9-4G data transmission module; 10-lithium battery; 11-methane sensor; 12-carbon dioxide sensor; 13-temperature sensor; 14-humidity sensor; 15-air pressure sensor. DETAILED DESCRIPTION

[0012] The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention fall within the scope of protection of the present invention.

[0013] Combined with attachment Figure 1 、 2 It can be seen that the floating box for continuous and automatic observation of lake carbon emission flux includes a float 1, an airtight float 2, and a control box 3; the airtight float 2 is a cylindrical hollow structure with a bottomless lower end and a closed top end, and the float 1 is a circular ring structure wrapped around and fixed to the outer periphery of the lower end of the airtight float 2 and keeps the lower end of the airtight float 2 open; a counterweight is set at the bottom of the float 1, and a plurality of solar panels 7 are evenly set on the float 1; the control box 3 is set on the top surface of the airtight float 2, and a lithium battery 10 and an Arduino micro-control computer 8 and a 4G data transmission module 9 connected to the control box 3 are set inside the control box 3; an air pump 5 is set on the top of the airtight float 2 and is connected to the Arduino micro-control computer 8 circuit, the air inlet of the air pump 5 is connected to the inside of the airtight float 2 and the air outlet corresponds to the outside air, and a pressure inlet is set under the side wall of the airtight float 2 A gas one-way valve 6; a circuit board 4 is provided on the top surface of the airtight float box 2 and is connected to the Arduino micro-control computer 8 circuit. A methane sensor 11, a carbon dioxide sensor 12, a temperature sensor 13, a humidity sensor 14, and an air pressure sensor 15 are fixedly provided on the circuit board 4 facing downward; the lithium battery 10 is used to store the electrical energy converted by the solar panel 7 and to power the Arduino micro-control computer 8, the 4G data transmission module 9, the circuit board 4, and the air pump 5; the user remotely controls the Arduino micro-control computer 8 through the 4G data transmission module 9 to set the time interval for the air pump 5 to perform air replacement and sensor data measurement, and can control the Arduino micro-control computer 8 to perform air replacement and data measurement at time intervals. The measured data is transmitted back to the data processing center by the 4G data transmission module 9.

[0014] The circuit board 4 is provided with a protective cover that can expose the methane sensor 11 , the carbon dioxide sensor 12 , the temperature sensor 13 , the humidity sensor 14 , and the air pressure sensor 15 .

[0015] The lithium battery 10 is a 12V 20Ah lithium battery.

[0016] The floating body 1 and the airtight buoyancy box 2 are connected in a fixed manner or in a detachable manner. The detachable connection makes it easier to replace the floating body 1.

[0017] Three solar panels 7 are evenly arranged on the floating body 1. With such arrangement, the solar panels 7 can more fully implement photoelectric conversion.

[0018] The model of the methane sensor 11 is Figaro NGM2611-E13. Although the detection range given by the manufacturer is 500~10000ppm, this model of sensor has been successfully used to measure the methane concentration in indoor environment (2~9ppm), and has the characteristics of low price and strong anti-interference ability, which is suitable for the present invention.

[0019] The model of the carbon dioxide sensor 12 is K33-ELG, which is produced by SenseAir. It is a manufacturer-pre-calibrated sensor with high measurement accuracy (up to 1 ppm) and a wide measurement range (0-5000 ppm), and is suitable for the present invention.

[0020] The control box 3 is a cylindrical structure or a cubic structure.

[0021] The volume of the airtight buoyancy tank 2 is 15-20L.

[0022] The side of the floating body 1 is provided with a connector for connecting a traction rope. With such a configuration, a traction rope can be set through the connector for fixing or recovering the floating body after deployment.

[0023] The working principle of this utility model:

[0024] The airtight float box 2 in the present invention is equivalent to the flux box in the prior art (hereinafter, when referring to the flux box and the airtight float box 2, the airtight float box 2 = flux box). The airtight float box 2 is set as a cylindrical structure to facilitate the calculation of parameters such as the headspace volume, the flux box cross-sectional area, and the flux box height; the airtight float box 2 is a cylindrical hollow structure with a bottomless lower end and a closed top end. When the airtight float box 2 is arranged on the water surface through the float 1, the airtight float box 2 is equivalent to being inverted on the water surface, forming an airtight structure inside, and the space above the water surface is the headspace area.

[0025] After the present invention is arranged in a water body, the airtight float box 2 enters an airtight state, and the methane and carbon dioxide in the water body continue to diffuse from the water into the headspace area of the airtight float box 2 through molecules, and the concentration gradually increases over time. Since the purpose of the observation is to obtain the emission of methane and carbon dioxide in the water body, if the airtight float box 2 remains airtight for a long time, the methane and carbon dioxide concentrations in the headspace will be too high, resulting in a large deviation from the actual environmental conditions or exceeding the sensor range. Therefore, the time interval for air replacement of the airtight float box 2 is usually set to 1 hour or 0.5 hours, and the time interval for sensor measurement during this period is usually set to once every 1 minute.

[0026] While the airtight float box 2 maintains an airtight state, the Arduino microcontroller 8 controls each sensor to measure once every minute, and the measured continuous data values are instantly transmitted back to the data processing center through the 4G data transmission module 9; the data processing center performs a linear fit on the continuous data values obtained during an airtight state period to obtain the slope k of the gas concentration change during the period. Based on the slope k, the methane and carbon dioxide emission fluxes F can be calculated, and the calculation formula is: F = k×headspace volume / flux box cross-sectional area; since the airtight float box 2 is a cylindrical structure, the flux box cross-sectional area can be negated, and the formula can be abbreviated as F = k×h, where h is the headspace height of the flux box.

[0027] When the air replacement time interval of the airtight float box 2 is reached, the Arduino micro-control computer 8 starts the air pump 5 to discharge the gas in the airtight float box 2. Under the suction pressure of the air pump 5, the pressure-type air inlet one-way valve 6 automatically opens due to the negative pressure, introducing low background concentration air from the environment. Through air replacement, the air in the top space area of the airtight float box 2 is made consistent with the ambient air. After the air replacement is completed, the airtight float box 2 enters the airtight state again, and each sensor continuously measures the data value of the time period again at the time interval and transmits it back to the data processing center. This cycle is repeated to achieve continuous and automatic observation of the methane and carbon dioxide emission fluxes at the water-air interface of the lake.

[0028] Application method of the utility model:

[0029] After completing the circuit and electrical connections of the relevant equipment and devices in the control box 3 and the airtight float 2, as well as the setting of the relevant accessories, the control box 3, the airtight float 2 and the floating body 1 (including the solar panel 7 and the counterweight, etc.) are assembled in sequence from top to bottom, and the connection can be fixed with screws and / or sealant during assembly; after adjusting the tilt angle of the solar panel 7 and powering on the equipment, the time intervals for air replacement and sensor measurement of the airtight float 2 can be preset in the Arduino micro-control computer 8, and the user can also remotely control the Arduino micro-control computer 8 to set the above time intervals through the 4G data transmission module 9; the utility model is then placed in the target water body, and its position can be fixed by a towing rope; then, under the control of the Arduino micro-control computer 8, the sensor measurement, air replacement and real-time data transmission are cyclically executed, and the data processing center calculates the gas concentration change slope k and the methane and carbon dioxide emission fluxes F in each time period.

[0030] In addition, the Figaro NGM2611-E13 methane sensor is a factory-precalibrated module based on the Figaro TGS 2611-E00. Factory calibration is performed at 5000 ppm, 20°C, and 65% RH. The methane concentration determination method of this utility model allows for indoor precalibration to ensure reliability during application. The calibration method is as follows:

[0031] A methane sensor was fixed to the headspace of a 20-liter plastic barrel inverted on the water surface. The headspace was connected to the measurement unit of a greenhouse gas analyzer (UGGA, Los Gatos Research) via two airtight plastic hoses, forming a closed circuit. The analyzer's built-in air pump thoroughly mixed the headspace gas within the circulating closed circuit. The measured methane concentration served as the standard reference value for the methane sensor.

[0032] Given the methane sensor module's sensitivity to temperature and humidity, calibration involves setting 10 temperature (4-45°C) and humidity (20-100%) gradients. Furthermore, considering the impact of temperature and humidity on methane readings, both temperature and humidity sensors are mounted on the circuit board to obtain real-time temperature and humidity data from the headspace of the plastic barrel. During calibration, the entire device is placed in a constant temperature chamber, and the ambient temperature in the headspace of the plastic barrel is changed by setting the constant temperature chamber temperature (the absolute humidity also changes with temperature). A syringe is used to inject methane gas directly into the headspace of the plastic barrel to change the methane concentration in the headspace. The methane concentration range during calibration is 2-1400 ppm, with multiple individual calibrations performed at different temperature and humidity levels of 4-45°C and 20-100%, with all data recorded once per minute.

Claims

1. A floating tank for continuous and automatic observation of lake carbon emission flux, characterized in that: The invention comprises a float (1), an airtight float box (2), and a control box (3); the airtight float box (2) is a cylindrical hollow structure with a bottomless lower end and a closed upper end, the float (1) is a circular ring structure wrapped around and fixed to the outer periphery of the lower end of the airtight float box (2) and keeps the lower end of the airtight float box (2) open; a counterweight is arranged at the bottom of the float (1), and a plurality of solar panels (7) are evenly arranged on the float (1); the control box (3) is arranged on the top surface of the airtight float box (2), and a lithium battery (10) and an Arduino micro-control computer (8) and a 4G data transmission module (9) are arranged inside the control box (3); an air pump (5) is arranged on the top of the airtight float box (2) and is connected to the Arduino micro-control computer (8) circuit, the air inlet of the air pump (5) is connected to the inside of the airtight float box (2) and the air outlet corresponds to the outside air, and a pressure-type air inlet check valve (6) is arranged below the side wall of the airtight float box (2); the air pump (5) is arranged on the top of the airtight float box (2) and is connected to the Arduino micro-control computer (8) circuit, the air inlet of the air pump (5) is connected to the inside of the airtight float box (2) and the air outlet corresponds to the outside air, and a pressure-type air inlet check valve (6) is arranged below the side wall of the airtight float box (2); A circuit board (4) is provided on the top surface of the airtight floating box (2) and is connected to the circuit of the Arduino micro-control computer (8). A methane sensor (11), a carbon dioxide sensor (12), a temperature sensor (13), a humidity sensor (14), and an air pressure sensor (15) are fixedly provided on the circuit board (4) facing downwards. The lithium battery (10) is used to store the electric energy converted by the solar panel (7) and to supply power to the Arduino micro-control computer (8), the 4G data transmission module (9), the circuit board (4), and the air pump (5). The user can remotely control the Arduino micro-control computer (8) through the 4G data transmission module (9) to set the time interval for the air pump (5) to perform air replacement and sensor data measurement, and can control the Arduino micro-control computer (8) to perform air replacement and data measurement at the time interval. The measured data is transmitted back to the data processing center by the 4G data transmission module (9).

2. The buoyancy chamber for continuous and automatic observation of lake carbon emission flux according to claim 1 is characterized in that: The circuit board (4) is provided with a protective cover capable of exposing the methane sensor (11), the carbon dioxide sensor (12), the temperature sensor (13), the humidity sensor (14), and the air pressure sensor (15).

3. The floating chamber for continuous and automatic observation of lake carbon emission flux according to claim 1 is characterized in that: The lithium battery (10) is a 12V 20Ah lithium battery.

4. The buoyancy chamber for continuous and automatic observation of lake carbon emission flux according to claim 1 is characterized in that: The floating body (1) and the airtight buoyancy box (2) are connected in a fixed or detachable manner.

5. The floating chamber for continuous and automatic observation of lake carbon emission flux according to claim 1 or 4, characterized in that: Three solar panels (7) are evenly arranged on the floating body (1).

6. The floating chamber for continuous and automatic observation of lake carbon emission flux according to claim 1 is characterized in that: The model of the methane sensor (11) is Figaro NGM2611-E13.

7. The floating chamber for continuous and automatic observation of lake carbon emission flux according to claim 1 is characterized in that: The model of the carbon dioxide sensor (12) is K33-ELG.

8. The floating chamber for continuous and automatic observation of lake carbon emission flux according to claim 1 is characterized in that: The control box (3) has a cylindrical structure or a cubic structure.

9. The floating chamber for continuous and automatic observation of lake carbon emission flux according to claim 1 or 4, characterized in that: The volume of the airtight floating box (2) is 15-20 L.

10. The floating chamber for continuous and automatic observation of lake carbon emission flux according to claim 1 or 4, characterized in that: A connector for connecting a traction rope is provided on the side of the floating body (1).

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