Apparatus and method for measuring dissolved radon concentration in seawater at different depths by bubbling

Abstract

An apparatus and method for measuring dissolved radon concentration in seawater at different depths using the bubbling method are disclosed. The apparatus includes a bubbling measurement bottle, a cap, an outlet pipe, an inlet pipe, a solenoid valve, a radon meter, a three-way valve, an air pump, a motor, a check valve, a weight, and a data acquisition and processing center. The bottom of the bottle is equipped with a water inlet, temperature and humidity sensors, a water pressure sensor, a salinity sensor, and a liquid level sensor. The inlet pipe, bubbling measurement bottle, outlet pipe, solenoid valve, radon meter, three-way valve, and air pump form an airflow loop. The motor is connected to the weight, and the temperature, humidity, water pressure sensors, salinity sensor, and pressure sensor are electrically connected to the data acquisition and processing center. By observing radon molecules entering or leaving the surface of the bubbling measurement bottle, the equilibrium concentration of radon in the air is measured and converted into the corresponding radon concentration in water to calculate the real-time dissolved radon concentration. This invention features a simple structure and convenient operation, enabling continuous real-time monitoring of changes in radon content in seawater, laying a solid foundation for marine radon research.

Description

Technical Field

[0001] This invention relates to the field of nuclear radiation detection technology, and in particular to a device and method for accurately measuring the concentration of dissolved radon in seawater at different depths in real time using a bubbling device. Background Technology

[0002] Nuclear and radiation safety environmental monitoring is a key area of ​​concern in my country, while the ocean also provides humanity with abundant marine resources. Radon, a daughter substance from the natural uranium-series decay chain, has a half-life of 3.82 days and is one of the most important naturally occurring radioactive nuclides, existing in nature as a water-soluble gas. Therefore, measuring the radon concentration in seawater is a meaningful task.

[0003] There are many methods for measuring radon concentration in water, and the methods vary greatly depending on the purpose and requirements. Commonly used methods recommended by ISO 13164 include liquid scintillation counting (LSC), gamma spectroscopy, and gas measurement (ISO 2013). Researchers have developed other methods, including diffusion, degassing membrane methods, and bubbling methods. In the bubbling method, the gas bubbling probe increases the contact area between water and gas, shortening the equilibrium time of radon concentration in the water and gas, thus making the bubbling method widely used.

[0004] Currently, the main methods for measuring dissolved gases in seawater include: sampling-laboratory analysis, in-situ measurement of dissolved gases in seawater based on optical sensing technology, and in-situ measurement technology based on hydrophobic and breathable membranes combined with gas sensing. Sampling-laboratory analysis primarily targets surface seawater dissolved gas measurement, using water samplers or sampling bottles to collect samples at different depths and locations during navigation. However, the data obtained from continuous measurements has poor temporal resolution. In-situ measurement technology based on optical sensing technology is a more advanced detection technique with significant application potential in areas with high dissolved gas concentrations. As a high-precision, non-contact measurement technology, it shows promising application prospects in the field of in-situ seawater measurement. In-situ measurement technology based on hydrophobic and breathable membranes combined with gas sensing uses a hydrophobic and breathable membrane to separate water vapor in situ, followed by gas sensing technology for measurement, achieving rapid and high-precision measurement of dissolved gases. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide an apparatus and method for measuring the dissolved radon concentration in seawater at different depths by bubbling method. This method can achieve continuous real-time monitoring of radon content in seawater without sampling the water body. It has high measurement and detection accuracy, simple process, convenient operation, and is stable and reliable.

[0006] The technical solution of the present invention is: a device for measuring the concentration of dissolved radon in seawater at different depths by bubbling method, comprising a bubbling measuring bottle, a bottle cap, an outlet pipe sleeve, a weight rope sleeve, an inlet pipe sleeve, an outlet pipe, an inlet pipe, a solenoid valve, a radon measuring instrument, a three-way valve, an air pump, a motor, a one-way valve, a weight, and a data acquisition and processing center.

[0007] The bubbling measuring bottle has a three-dimensional conical structure with multiple water inlets at the bottom. Temperature, humidity, water pressure, and salinity sensors are located at the bottom inside the bubbling measuring bottle. A pressure sensor is located at the air inlet of the radon measuring instrument. Two liquid level sensors are located on the upper and lower inner walls of the bubbling measuring bottle, respectively.

[0008] The outlet pipe sleeve, weight rope sleeve, and inlet pipe sleeve are respectively installed on the bottle cap. The outlet pipe is inserted into the outlet pipe sleeve, and the inlet pipe is inserted into the inlet pipe sleeve. The inlet pipe extends into the bottom of the bubbling measuring bottle. The inlet end of the outlet pipe extends into the bubbling measuring bottle. The outlet end of the outlet pipe is connected to the inlet end of the radon measuring instrument through a solenoid valve. The outlet end of the radon measuring instrument is connected to the first inlet of the three-way valve. The second inlet of the three-way valve is connected to the atmosphere. The outlet of the three-way valve is connected to the inlet end of the air pump. The outlet end of the air pump is connected to the inlet of the one-way valve. The outlet of the one-way valve is connected to the inlet end of the inlet pipe.

[0009] The motor output end suspends a heavy object via a traction rope. The traction rope passes through the weight rope loop on the bottle cap and the water inlet at the bottom of the bubbling measuring bottle, causing the heavy object to sink into the seawater. The solenoid valve, radon measuring instrument, three-way valve, air pump, motor, temperature, humidity and water pressure sensors, salinity sensor, pressure sensor, and two liquid level sensors are electrically connected to the data acquisition and processing center via wired or wireless means.

[0010] A further technical solution of the present invention is that the end of the air inlet pipe that extends into the bubbling measuring bottle is a porous cavity.

[0011] Another technical solution of the present invention is: a method for measuring the dissolved radon concentration in seawater at different depths using the aforementioned bubbling method, comprising a measurement process and a calculation process.

[0012] I. Measurement Process

[0013] The weight at the lower end of the motor traction rope is submerged in the water. Seawater enters the bubble measuring bottle through the water inlet at the bottom. The data from the two liquid level sensors control the three-way valve, air pump, and check valve, causing the device for measuring the dissolved radon concentration in seawater at different depths using the bubble method to sink to the depth of the seawater where the radon concentration is to be measured.

[0014] Open the solenoid valve and check valve, start the air pump, and connect the first air inlet and outlet of the three-way valve. The bubbles that bulge out of the bubbling measurement bottle come into contact with the seawater in the bubbling measurement bottle and bulge out from the liquid surface in the bubbling measurement bottle. They enter the radon measuring instrument through the air outlet pipe and solenoid valve, and flow out of the radon measuring instrument into the three-way valve, air pump, and check valve, and finally flow back into the bubbling measurement bottle to form an airflow loop.

[0015] After the airflow stabilizes, the radon measuring instrument measures the radon concentration in the bubbling gas; and sends the measured temperature, water pressure at the bottom of the bubbling measuring bottle, salinity, pressure in the upper space of the bubbling measuring bottle, and liquid level position signals of the bubbling measuring bottle to the data acquisition and processing center.

[0016] II. Calculation Process

[0017] When measuring the concentration of dissolved radon in seawater, it is necessary to measure the solubility of radon and convert the concentration from the gas phase to the water phase; the concentration of radon in the atmosphere and water phase remains constant over time, and a radon concentration equilibrium is reached between water and circulating air.

[0018] Substitute the measured temperature and salinity into the following... 222 The solubility coefficient K0 of radon is calculated from the air-water partition coefficient of Rn and the empirical equations for water temperature and salinity:

[0019]

[0020] Where T is the temperature measured by the temperature, humidity, and water pressure sensors, in Kelvin; S is the salinity measured by the salinity sensor, in grams per kilogram; and K0 is the solubility coefficient of radon, in mol (L·atm). -1 .

[0021] Substituting the radon solubility coefficient K0 calculated by formula (1) into the following formula, the radon distribution coefficient in water / air at radon equilibrium is calculated:

[0022]

[0023] Since the radon concentration measured by the radon meter is the data when radon reaches water / air equilibrium, the radon equilibrium concentration in the air measured by the radon meter is converted into the corresponding radon concentration in water, thus obtaining the radon concentration in seawater at that depth. The calculation formula is as follows:

[0024] C water =C air *K w / air (3)

[0025] Among them, C water The concentration of radon in water is expressed in Bq / L; C air This represents the concentration of radon in the gaseous phase, expressed in Bq / L.

[0026] A further technical solution of the present invention is: the calculation process also includes calculating the depth of the bubbling measuring bottle based on the water pressure at the bottom of the bubbling measuring bottle measured by temperature, humidity and water pressure sensors, and the specific calculation formula is as follows:

[0027]

[0028] Where Z is the depth of the bubbling measuring bottle, in meters; P is the underwater pressure measured by the temperature, humidity and water pressure sensors, in decibars, where 1 decibar = 0.01 MPa; and L is the latitude of the bubbling measuring bottle, in degrees.

[0029] Compared with the prior art, the present invention has the following characteristics:

[0030] The device for measuring radon concentration according to this invention has a simple structure and is easy to use, requiring no water sampling and greatly saving measurement costs. The method for measuring radon concentration according to this invention is simple in process and highly sensitive, reducing various factors that affect the radon observation data in seawater and improving measurement accuracy. This invention can achieve continuous real-time detection to monitor changes in radon content in seawater, making the radon observation data in seawater more stable and accurate.

[0031] The detailed structure of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0032] Appendix Figure 1 This is a schematic diagram of the radon concentration measuring device according to Embodiment 1 of the present invention;

[0033] Appendix Figure 2 This is a schematic diagram of the bottom structure of the bubbling device;

[0034] Appendix Figure 3 This is a schematic diagram of the radon concentration measuring device according to Embodiment 2 of the present invention. Detailed Implementation

[0035] Example 1: A device for measuring dissolved radon concentration in seawater at different depths using the bubbling method, comprising a bubbling measuring bottle 1, a bottle cap 2, an outlet pipe sleeve 3, a weight rope sleeve 4, an inlet pipe sleeve 5, an outlet pipe 6, an inlet pipe 7, a solenoid valve 8, a radon measuring instrument 9, a three-way valve 10, an air pump 11, a motor 12, a one-way valve 13, a weight 14, and a data acquisition and processing center (not shown in the figure).

[0036] The bubbling measuring bottle 1 has a three-dimensional conical structure with multiple water inlets 1-1 at its bottom. When the bubbling measuring bottle 1 is placed in seawater, seawater can enter the interior of the bubbling measuring bottle 1 through the multiple water inlets 1-1. Temperature, humidity, and water pressure sensors 15 and a salinity sensor 16 are located at the bottom of the bubbling measuring bottle 1 to measure the temperature T and water pressure F1 at the bottom of the bubbling measuring bottle 1, as well as the salinity S of the seawater. A pressure sensor 17 is located at the air inlet of the radon measuring instrument 9. During measurement, the air inlet section is connected to the upper space of the bubbling measuring bottle 1, and the pressure F2 in the upper space of the bubbling measuring bottle 1 can be accurately determined through the reading of the pressure sensor 17. Two liquid level sensors 18 are respectively located on the upper and lower inner walls of the bubbling measuring bottle 1 to define the upper and lower limits of the liquid level in the bubbling measuring bottle 1.

[0037] The air outlet sleeve 3, the weight rope sleeve 4, and the air inlet sleeve 5 are respectively installed on the bottle cap 2. The air outlet pipe 6 is inserted into the air outlet sleeve 3, and the air inlet pipe 7 is inserted into the air inlet sleeve 5. The air inlet pipe 7 extends into the bottom of the bubbling measuring bottle 1 to facilitate sufficient contact between the air entering from the air inlet pipe 7 and the seawater. The air inlet end of the air outlet pipe 6 extends into the bubbling measuring bottle 1, and the air outlet end of the air outlet pipe 6 is connected to the air inlet end of the radon measuring instrument 9 through the solenoid valve 8. The air outlet end of the radon measuring instrument 9 is connected to the first air inlet A of the three-way valve 10. The second air inlet C of the three-way valve 10 is connected to the atmosphere. The air outlet B of the three-way valve 10 is connected to the air inlet end of the air pump 11. The air outlet end of the air pump 11 is connected to the air inlet of the one-way valve 13. The air outlet of the one-way valve 13 is connected to the air inlet end of the air inlet pipe 7. The output end of motor 12 suspends a weight 14 via a traction rope. The traction rope passes through the weight rope loop 4 on the bottle cap 2 and the water inlet 1-1 at the bottom of the bubbling measuring bottle 1, causing the weight 14 to sink into the seawater, thereby reducing the impact of underwater ocean current disturbances on the device during the measurement process. The solenoid valve 8, radon measuring instrument 9, three-way valve 10, air pump 11, motor 12, temperature, humidity and water pressure sensors 15, salinity sensor 16, pressure sensor 17, and two liquid level sensors 18 are electrically connected to the data acquisition and processing center via wired or wireless means for data transmission and processing.

[0038] Example 2 is basically similar in structure to Example 1, except that, as shown in Example 2... Figure 3 As shown, in order to facilitate the generation of more bubbles from the air entering through the air inlet pipe 7 and to allow them to come into contact with the water in the bubbling measuring bottle 1, the end of the air inlet pipe 7 that extends into the bubbling measuring bottle 1 is designed as a porous cavity.

[0039] Example 3: A method for measuring the concentration of dissolved radon in seawater at different depths using the bubbling method applied in Example 1 or Example 2, including the measurement process and the calculation process.

[0040] I. Measurement Process

[0041] The weight 14 at the lower end of the traction rope of the motor 12 is submerged in the water. Seawater enters the bubble measuring bottle 1 through the water inlet 1-1 at the bottom of the bubble measuring bottle 1. The data from the two liquid level sensors 18 are used to control the three-way valve 10, the air pump 11 and the one-way valve 13, so that the device for measuring the dissolved radon concentration in seawater at different depths by the bubble method sinks into the seawater at the depth of the radon concentration to be measured.

[0042] The specific operating procedure for sinking the device into seawater at the depth required to measure radon concentration is as follows: The solenoid valve 8 is closed, and the motor 12 controls the weight 14 at the lower end of the traction rope to sink the device. When the liquid surface inside the device contacts the higher-positioned liquid level sensor 18, the motor 12 stops working, and the weight 14 stops sinking. The air pump 11 is turned on, connecting the second air inlet C and the air outlet B of the three-way valve 10, pumping external air into the upper space of the device through the air pump 11 and the one-way valve 13, increasing the air pressure in the upper space of the bubbling measuring bottle 1, causing the liquid surface inside to move downwards. When the liquid surface touches the lower-positioned liquid level sensor 18, the air pump 11 is turned off, and the motor 12 controls the weight 14 at the lower end of the traction rope to continue pulling the device downwards. This process is repeated until the desired measurement depth is reached.

[0043] Open the solenoid valve 8 and the one-way valve 13, start the air pump 11, and connect the first air inlet A and the air outlet B of the three-way valve 10. Under the action of the air pump 11, the bubbles bulging out of the bubble measuring bottle 1 enter the radon measuring instrument 9 through the air outlet pipe 6 and the solenoid valve 8, and flow out of the radon measuring instrument 9 into the three-way valve 10, the air pump 11, and the one-way valve 13, and finally flow back into the bubble measuring bottle 1 to form an airflow loop.

[0044] Bubbles bulging from the bottom of the inlet pipe 7 come into contact with seawater in the bubbling measuring bottle 1 and then bubble out from the liquid surface inside the bottle 1. After contacting the seawater, the bubbles enter the radon measuring instrument 9 through the outlet pipe 6. Once the airflow stabilizes, the radon measuring instrument 9 measures the radon concentration C in the bulging gas. air ; and the radon concentration C air The temperature T, water pressure F1 at the bottom of the bubbling measuring bottle 1, salinity S, pressure F2 in the upper space of the bubbling measuring bottle 1, and liquid level position signals of the temperature, humidity and water pressure sensor 15, salinity sensor 14, pressure sensor 15 and two liquid level sensors 18 are respectively sent to the data acquisition and processing center.

[0045] II. Calculation Process

[0046] When measuring the concentration of dissolved radon in seawater, it is necessary to measure the solubility of radon and convert the concentration from the gas phase to the water phase. Radon molecules continuously enter or leave the ocean surface, and when the exchange rate is equal, an equilibrium state is reached. At this time, the concentration of radon in the atmosphere and water phase remains unchanged over time, and the radon concentration is in equilibrium between water and circulating air.

[0047] Substitute the measured temperature T and salinity S into the following...222 The solubility coefficient K0 of radon is calculated from the air-water partition coefficient of Rn and the empirical equations for water temperature and salinity:

[0048]

[0049] Where T is the temperature measured by temperature, humidity and water pressure sensor 15, in Kelvin; S is the salinity measured by salinity sensor 16, in grams per kilogram; and K0 is the solubility coefficient of radon, in mol (L·atm). -1 .

[0050] Substituting the radon solubility coefficient K0 calculated by formula (1) into the following formula, the radon distribution coefficient in water / air at radon equilibrium is calculated:

[0051]

[0052] Since the radon concentration measured by the radon measuring instrument 9 is the data when radon reaches water / air equilibrium, the radon equilibrium concentration in the air measured by the radon measuring instrument 9 is converted into the corresponding radon concentration in water, thus obtaining the radon concentration in seawater at that depth. The calculation formula is as follows:

[0053] C water =C air *K w / air (3)

[0054] Among them, C water The concentration of radon in water is expressed in Bq / L; C air This represents the concentration of radon in the gaseous phase, expressed in Bq / L.

[0055] An apparatus for measuring dissolved radon concentration in seawater at different depths using the bubbling method can calculate the dissolved radon concentration when the apparatus is placed in seawater at different depths.

[0056] Example 4 is similar to Example 3 in that the calculation process also includes calculating the depth of the bubbling measuring bottle 1 based on the water pressure F1 at the bottom of the bubbling measuring bottle 1 and the pressure F2 in the upper space of the bubbling measuring bottle 1 measured by the temperature and humidity sensor 15. The specific calculation formula is as follows:

[0057]

[0058] Where Z is the depth of the bubbling measuring bottle 1, in meters; P is the underwater pressure measured by the temperature, humidity and water pressure sensor 15, in decibar, where 1 decibar = 0.01 MPa; and L is the latitude of the bubbling measuring bottle 1, in degrees.

Claims

1. A method for measuring dissolved radon concentration in seawater at different depths using the bubbling method, characterized by: Including the measurement process and the calculation process, I. Measurement Process The weight at the lower end of the motor traction rope is submerged in the water. Seawater enters the bubble measuring bottle through the water inlet at the bottom of the bubble measuring bottle. The data from the two liquid level sensors control the three-way valve, air pump, and check valve, so that the device for measuring the dissolved radon concentration in seawater at different depths by the bubble method sinks into the seawater at the depth of the radon concentration to be measured. Open the solenoid valve and check valve, start the air pump, and connect the first air inlet and outlet of the three-way valve. The bubbles that are bubbling out of the bubbling measurement bottle come into contact with the seawater in the bubbling measurement bottle and bubble out from the liquid surface in the bubbling measurement bottle. They enter the radon measuring instrument through the air outlet pipe and solenoid valve, and flow out of the radon measuring instrument into the three-way valve, air pump, and check valve, and finally flow back into the bubbling measurement bottle to form an airflow loop. After the airflow stabilizes, the radon measuring instrument measures the radon concentration in the bubbling gas; and sends the measured temperature, water pressure at the bottom of the bubbling measuring bottle, salinity, pressure in the upper space of the bubbling measuring bottle, and liquid level position signals of the bubbling measuring bottle to the data acquisition and processing center. II. Calculation Process When measuring the concentration of dissolved radon in seawater, it is necessary to measure the solubility of radon and convert the concentration from the gas phase to the water phase; the concentration of radon in the atmosphere and water phase remains constant over time, and a radon concentration equilibrium is reached between water and circulating air; Substitute the measured temperature and salinity into the following... 222 The solubility coefficient K0 of radon is calculated from the air-water partition coefficient of Rn and the empirical equations for water temperature and salinity: Where T is the temperature measured by the temperature, humidity, and water pressure sensors, in Kelvin; S is the salinity measured by the salinity sensor, in grams per kilogram; and K0 is the solubility coefficient of radon, in mol (L·atm). -1 ; Substituting the radon solubility coefficient K0 calculated by formula (1) into the following formula, the radon distribution coefficient in water / air at radon equilibrium is calculated: Since the radon concentration measured by the radon meter is the data when radon reaches water / air equilibrium, the radon equilibrium concentration in the air measured by the radon meter is converted into the corresponding radon concentration in water, thus obtaining the radon concentration in seawater at that depth. The calculation formula is as follows: C water =C air *K w / air (3) Among them, C water The concentration of radon in water is expressed in Bq / L; C air This represents the concentration of radon in the gaseous phase, expressed in Bq / L.

2. The method for measuring dissolved radon concentration in seawater at different depths using the bubbling method as described in claim 1, characterized in that: The calculation process also includes calculating the depth of the bubbling measuring bottle based on the water pressure at the bottom of the bubbling measuring bottle measured by temperature, humidity, and water pressure sensors. The specific calculation formula is as follows: Where Z is the depth of the bubbling measuring bottle, in meters; P is the underwater pressure measured by the temperature, humidity and water pressure sensors, in decibars, where 1 decibar = 0.01 MPa; and L is the latitude of the bubbling measuring bottle, in degrees.

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