JP2021071385A - Measurement system - Google Patents

Abstract

To provide a measurement system that measures the concentration of a dissolving material as a measurement target in a liquid by measuring the amount of the material in a gas.SOLUTION: The present invention relates to a housing 11 including a passage region that allows passage of at least gas and a non-passage region that makes passage of liquid and gas impossible; a measurement sensor in the housing 11, the sensor measuring the amount of the dissolving material in a liquid in contact with the passage region in the housing 11; and an operation device 20 for operating the concentration of the dissolving material in the liquid on the basis of the information of the material measured by the measurement sensor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a measuring system that measures the concentration of a dissolved substance in a liquid in a gaseous environment.

For example, in fish farming, the underwater condition of the fish is greatly affected by the fish growing environment. As an example, if the concentration of ammonia in the water rises, the fish may stop growing or, in the worst case, die. Therefore, a sensor for measuring ammonia in water is known, but there is a problem that the sensor deteriorates immediately when it is measured in water, and maintenance requires a great deal of labor and cost.

Further, for example, the techniques shown in Patent Documents 1 to 3 are disclosed as a technique for measuring ammoniacal nitrogen in water with ammonia gas. The technique shown in Patent Document 1 is a method for analyzing ammonia nitrogen in water, which comprises volatilizing ammonia nitrogen as ammonia gas by making a water sample containing ammonia nitrogen strongly alkaline and quantifying the ammonia. Ammonia gas is volatilized by adjusting the pH of the sample to 12 or higher with a strong alkali and heating it to a temperature of 80 ° C. or lower, and the generated ammonia gas is led out to the ammonia detection unit by the inert carrier gas to detect and quantify ammonia. It is a thing.

The technique shown in Patent Document 2 takes in an alkalizing means for making the sample water supplied through the sample water supply channel alkaline to generate ammonia gas from ammonium ions in the sample water, and an ammonia gas generated by the alkalizing means. It is provided with a measuring instrument having an ammonia sensor that dissociates the ammonia gas into ammonium ions and hydroxyl groups and detects the concentration of ammonium ions contained in the sample water based on the concentration of the hydroxyl groups. ..

In the technique shown in Patent Document 3, the detector mixes and contacts the test water and the alkali in the mixer to liberate the ammoniacal nitrogen contained in the test water as ammonia gas, and then in the separation column ammonia gas permeation separation column. Ammonia gas is separated and reacted with the carrier (acid) supplied from the carrier tank, and the amount of change in the internal potential (voltage) of the carrier accompanying this reaction is measured. The measured voltage is the ammonia nitrogen concentration calculation. The detector is stored in a constant temperature bath to maintain the measurement performance, and the water test water supply system has a cleaning liquid supply function for column cleaning and the detector calibration. It is provided with a calibration solution supply function for.

Japanese Unexamined Patent Publication No. 58-47254 Japanese Unexamined Patent Publication No. 8-189925 Japanese Unexamined Patent Publication No. 2001-50932

However, the techniques shown in the above patent documents have a problem that the sample to be measured needs to be adjusted to be alkaline or heated, which takes time and effort. In addition, for example, in the case of measuring the ammonia concentration in water in a fish farm, it is necessary for the collector to take preparatory work such as entering the water in order to collect a sample in the central part of the farm. There is a problem that it takes a lot of time and effort to obtain the distribution of ammonia concentration.

The present invention provides a measuring system for determining the concentration of a dissolved substance to be measured in a liquid by measuring the amount of the substance in the gas.

The measurement system according to the present invention is disposed in a housing formed of at least a distribution region that enables the flow of gas and a non-circulation region that disables the flow of liquid and gas, and is arranged in the housing. The concentration of the dissolved substance in the liquid based on the measurement sensor for measuring the amount of the dissolved substance contained in the liquid in contact with the flow area in the housing and the information on the amount of the substance measured by the measuring sensor. It is provided with a calculation means for calculating.

As described above, in the measurement system according to the present invention, at least the housing formed from the distribution region that enables the flow of gas and the non-distribution region that disables the flow of liquid and gas, and the distribution region are in contact with each other. Since it is provided with a measuring sensor for measuring the amount of the dissolved substance contained in the liquid in the housing and a calculation means for calculating the concentration of the dissolved substance in the liquid based on the measured information on the amount of the substance, the measuring sensor is provided. It is possible to detect the concentration of the dissolved substance in the liquid without immersing the gas in the liquid, and it is possible to prolong the life of the measurement sensor and minimize the labor and cost of maintenance.

It is a figure which shows the system structure of the measurement system which concerns on 1st Embodiment. It is a schematic diagram which shows the structure of the sensor part in the measurement system which concerns on 1st Embodiment. It is a figure which shows an example of the hardware composition of the arithmetic unit in the measurement system which concerns on 1st Embodiment. It is a figure which shows the principle of the measurement system which concerns on 1st Embodiment. It is a 1st functional block diagram of the measurement system which concerns on 1st Embodiment. It is a figure which shows the simulation result of the measurement system which concerns on 1st Embodiment. It is a 2nd functional block diagram of the measurement system which concerns on 1st Embodiment. It is a 3rd functional block diagram of the measurement system which concerns on 1st Embodiment. It is a schematic diagram which shows the structure of the sensor part in the measurement system which concerns on 2nd Embodiment. It is a schematic diagram which shows the structure of the sensor part in the measurement system which concerns on 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described. In addition, the same elements are designated by the same reference numerals throughout the present embodiment.

(First Embodiment of the present invention)
The measurement system according to this embodiment will be described with reference to FIGS. 1 to 8. The measurement system according to the present embodiment detects the concentration of a dissolved substance contained in a liquid in a gaseous state. In this embodiment, for example, a measurement system for detecting the ammonia concentration in a catfish farm in a gas state in a sealed housing will be specifically described.

FIG. 1 is a diagram showing a system configuration of a measurement system according to the present embodiment. The measurement system 1 includes a sensor unit 10 installed in a farm where aquaculture is cultivated, and a calculation device 20 that receives information measured by the sensor unit 10 and calculates the ammonia concentration in the farm. The unit 10 and the arithmetic unit 20 are in a state where data communication can be performed wirelessly or by wire with each other. The sensor unit 10 is installed in a state where at least a part of the sensor unit is immersed in the water of the farm, and detects the amount of substance (or the number of molecules) of ammonia in the gas in the process of vaporizing the water content of the farm. The detected substance amount information is transmitted to the arithmetic unit 20 in real time or collectively, and the arithmetic unit 20 calculates the ammonia concentration in the water of the farm.

FIG. 2 is a schematic view showing the structure of the sensor unit in the measurement system according to the present embodiment. The sensor unit 10 includes at least a rectangular upper surface portion 11A as a flow region that allows gas to flow, and a rectangular side surface portion 11B and a bottom surface portion 11C as non-circulation regions that prevent liquid and gas from flowing. Ammonia sensor that measures the amount of substance of ammonia contained in the housing 11 and the gas that is stored in the housing 11 and is vaporized with the water to be measured (water from the farm and contains various components). A transmitter 13 and a transmitter 13 for transmitting the result measured by the ammonia sensor 12 to the arithmetic unit 20 are provided.

A moisture-permeable waterproof sheet 14 that at least permeates gaseous water vapor and does not permeate liquid water is attached to the upper surface portion 11A, which is a distribution region, to prevent moisture from flowing into the housing 11 and to prevent moisture from flowing into the housing 11. Water vapor evaporating from the upper surface portion 11A is stored inside the housing 11.

As will be described later, the sensor unit 10 is immersed in water from the upper surface portion 11A side in the used state. Therefore, when the state is stable, moisture does not flow into the housing 11 due to air pressure even if the moisture permeable waterproof sheet 14 is not attached, but the housing 11 is tilted due to waves, vibrations, etc., or due to fish. When a water flow occurs, the balance of the housing 11 is lost and water flows into the housing 11. Therefore, the moisture-permeable waterproof sheet 14 does not necessarily have to be attached to the distribution area, but in order to more reliably prevent the inflow of moisture into the housing 11, the moisture-permeable waterproof sheet 14 is attached to the distribution area. It is desirable to be done.

Further, in the present embodiment, the upper surface portion 11A is a distribution region and the side surface portion 11B and the bottom surface portion 11C are non-distribution regions, but the distribution region and the non-distribution region can be arranged in any portion, and a plurality of regions can be arranged. May reach. That is, when a part or all of the housing 11 is submerged, at least the inside of the housing 11 is sealed, and the gas inside the housing 11 is formed through the moisture permeable waterproof sheet 14 or directly. A distribution area and a non-distribution area may be provided so as to come into contact with water in the water.

An ammonia sensor 12 is arranged in the housing 11 to measure the amount of substance of ammonia vaporized in the housing 11 together with water vapor from water via a distribution region. Since the inside of the housing 11 is a closed space, it takes a predetermined time to reach a gas-liquid equilibrium state, and eventually becomes saturated. Although details will be described later, in the present invention, the ammonia concentration in water is calculated from the sensing result of the ammonia sensor 12 from the time when the distribution region is immersed in water until the ammonia is saturated.

The transmitter 13 transmits the result of sensing by the ammonia sensor 12 to the arithmetic unit 20. Further, as will be described later, when a temperature sensor or a barometric pressure sensor is installed in the housing 11, the information is also collectively transmitted to the arithmetic unit 20. Although the ammonia sensor 12 and the transmitter 13 are shown as separate parts in FIG. 2, they may be integrated into the ammonia sensor 12 with a communication function.

FIG. 3 is a diagram showing an example of the hardware configuration of the arithmetic unit 20. As the arithmetic unit 20, for example, a general personal computer (PC), a tablet terminal, a mobile terminal, or the like can be used. In FIG. 3, the arithmetic unit 20 includes a CPU 210, a RAM 220, a ROM 230, a hard disk (referred to as HD) 240, a communication I / F 250, and an input / output I / F 260. An operating system, a program, a database, and the like are stored in the ROM 230 and HD 240, and the program is read into the RAM 220 as needed and executed by the CPU 210.

The communication I / F 250 is an interface for performing communication such as receiving information from a transmitter 13, for example. The input / output I / F 260 is an interface for accepting input from input devices such as a touch panel, keyboard, and mouse, and outputting data to a printer, a display, or the like. The input / output I / F 260 can be connected to a drive compatible with a magneto-optical disk, a removable disk such as a CD-R, a DVD-R, or the like, if necessary. Each processing unit is connected via a bus and exchanges information. The above hardware configuration is just an example and can be changed as needed.

FIG. 4 is a diagram showing the principle of the measurement system according to the present embodiment. FIG. 4A shows a case where a part of the sensor unit 10 is immersed in water, and FIG. 4B shows a case where the entire sensor unit 10 is immersed in water. In the used state, as shown in FIG. 4, the housing 11 is immersed in the water to be measured with the upper surface portion 11A, which is the distribution region, facing down. At this time, the liquid and the gas are installed in water so that they can intervene at least in the space of the distribution region so as to sandwich the boundary (the moisture permeable waterproof sheet 14 when the moisture permeable waterproof sheet 14 is provided).

At the boundary portion of the distribution region, evaporation and condensation are performed in both cases of FIGS. 4 (A) and 4 (B), and eventually a vapor-liquid equilibrium state (saturated state) is reached. Various components are dissolved in the water of the farm, one of which is ammonia. At this time, if the ammonia concentration in water is high, the time until ammonia is saturated in the housing 11 is short, and if the ammonia concentration in water is low, the time until ammonia is saturated in the housing 11 is long. In the present embodiment, the concentration of ammonia in water is determined by measuring the change in the amount of substance of ammonia per predetermined unit time in the housing 11.

FIG. 5 is a first functional block diagram of the measurement system according to the present embodiment. The sensor unit 10 includes an ammonia sensor 12 and a transmitter 13, and the sensing result of the ammonia sensor 12 is transmitted to the arithmetic unit 20 by the transmitter 13. At this time, for example, the transmitter 13 may transmit the sensing result of the ammonia sensor 12 to the arithmetic unit 20 every predetermined unit time (for example, about several seconds to several minutes), or the ammonia sensor 12 may transmit the sensing result. Sensing may be performed at predetermined unit times and the result may be passed to the transmitter 13, or the sensing result of the ammonia sensor 12 may be constantly transmitted by the transmitter 13 in real time.

The arithmetic unit 20 includes an arithmetic unit 21 that calculates the ammonia concentration in water from the measurement result transmitted from the sensor unit 10, and an output control unit 22 that outputs the arithmetic result to the display 30 or the like. As described above, the arithmetic unit 20 calculates the ammonia concentration in water based on the change in the amount of substance of ammonia per unit time transmitted from the sensor unit 10. Specifically, it is possible to calculate the ammonia concentration in water by the following calculation method.

m (t) is the amount of ammonia substance at time t in the housing 11, α is the correction coefficient of the measurement environment, and β is the offset value. As a result, the ammonia concentration in water can be obtained from the change in the amount of ammonia substance in the housing 11 at time t. In addition, α and β are arbitrarily set according to the characteristics of the apparatus and the measurement environment. Here, the simulation result based on the above calculation is shown in FIG. In FIG. 6, the horizontal axis is time and the vertical axis is the saturation rate in the housing 11 (when the saturation state is 1, the ratio of the amount of ammonia in the housing 11 to the saturated state is shown) in water. The relationship between the time and the saturation rate in the housing 11 in each case where the ammonia concentration is 1 ppm to 10 ppm is shown. As is clear from FIG. 6, the higher the ammonia concentration in water, the more saturated the inside of the housing 11 is in a short time. That is, it is possible to obtain the ammonia concentration in water from the change in the amount of substance of ammonia until the inside of the housing 11 is saturated. The simulation results shown in FIG. 6 are shown as an example only, and in actual measurement, different results may be obtained due to differences in environmental parameters and the like.

The ammonia concentration in the water calculated in this way is displayed on the display 30. At this time, if the concentration is equal to or higher than the preset concentration (more than the concentration that may affect the fish being cultivated if the concentration becomes higher than this), the output control unit 22 outputs with a warning. It may be. It is desirable that the warning is in a form that appeals to the eyes and hearing such as sound, color, and blinking.

FIG. 7 is a second functional block diagram of the measurement system according to the present embodiment. The difference from the configuration of FIG. 5 is that the storage unit 23 newly stores the change in the amount of substance per unit time until the amount of substance of ammonia in the housing 11 converges according to the concentration of ammonia in water. The calculation unit 21 extracts the ammonia concentration corresponding to the sensing result transmitted from the sensor unit 10 from the storage unit 23. That is, when the ammonia concentration in water is X%, the storage unit 23 stores information such as Ymol of the change in the amount of substance of ammonia per unit time in the housing 11, and the measurement by the sensor unit 10. It is possible to extract the ammonia concentration X% from the Ymol information obtained in.

Here, the change in the amount of substance of ammonia per unit time in the housing 11 depends on the saturated vapor pressure, and therefore differs depending on the temperature and the atmospheric pressure. That is, by measuring the temperature and / or atmospheric pressure at the time of measurement and calculating the ammonia concentration in water from the change in the amount of substance of ammonia per unit time in the housing 11 at each temperature and / or atmospheric pressure, it is more accurate. It becomes possible to ask. FIG. 8 is a third functional block diagram of the measurement system according to the present embodiment. What is different from the configuration of FIG. 7 is that the housing 11 is provided with a temperature sensor 15 for measuring the temperature inside the housing 11 and a pressure sensor 16 for measuring the pressure, and the transmitter 13 senses the result of the ammonia sensor 12. At the same time, the measurement results of the temperature sensor 15 and the pressure sensor 16 are also transmitted to the arithmetic unit 20. In the calculation device 20, the storage unit 23 stores Ymol of the change in the amount of substance of ammonia per unit time in the housing 11 according to the ammonia concentration X% in water at a predetermined temperature T ° C. and a predetermined pressure PhPa. Based on the changes in the temperature, pressure, and amount of substance of ammonia transmitted from the sensor unit 10, the unit 21 extracts the corresponding ammonia concentration from the storage unit 23.

In this way, it is possible to obtain a more accurate ammonia concentration by considering the temperature and atmospheric pressure. In addition, in FIG. 8, the storage unit 23 is configured to store the change in the amount of substance of ammonia per unit time in the housing 11 according to the ammonia concentration in water at a predetermined temperature and a predetermined atmospheric pressure. As in the case, the ammonia concentration in water may be obtained by the following calculation.

m (t) is the amount of ammonia substance at time t in the housing 11, τ is the temperature coefficient, ρ is the pressure coefficient, α is the correction coefficient of the measurement environment, and β is the offset value. As a result, in addition to the change in the amount of ammonia substance in the housing 11 at time t, the concentration in water in consideration of the temperature and atmospheric pressure at the time of measurement can be obtained.

Further, in FIG. 8, the sensor unit 10 is provided with the temperature sensor 15 and the barometric pressure sensor 16, but it may be configured to include only one of them. In that case, the storage unit 23 may store the change in the amount of substance of ammonia per unit time in the housing 11 according to the concentration of ammonia in water at either a predetermined temperature or a predetermined atmospheric pressure.

As described above, in the measurement system according to the present embodiment, the housing 11 formed from at least the distribution region that enables the flow of gas and the non-distribution region that disables the flow of liquid and gas, and the distribution region. It is provided with an ammonia sensor 12 for measuring the amount of substance in the housing 11 of ammonia contained in the water in contact with the water, and a calculation unit 21 for calculating the concentration of ammonia in water based on the measured information on the amount of substance. Therefore, it is possible to detect the concentration of ammonia in the water without immersing the ammonia sensor 12 in the water, and the ammonia sensor 12 can be made to last for a long time, and the labor and cost of maintenance can be minimized.

Further, since the concentration of ammonia is calculated based on the amount of change in the amount of substance per predetermined time in the state before the amount of substance of ammonia in the housing 11 converges (or is saturated), the amount of ammonia in the housing 11 is calculated. It is possible to estimate the concentration of ammonia in water by using the change in the amount of substance until saturation (when the concentration of ammonia in water is high, it goes to saturation in a short time, and when it is low, it takes a long time). ..

Further, since the storage unit 23 stores the change in the amount of substance per predetermined time until the amount of substance of ammonia in the housing 11 converges according to the concentration of ammonia in water, the ammonia in the housing 11 is provided. The concentration of ammonia in the corresponding water can be extracted from the storage unit 23 by utilizing the change in the amount of substance until the substance is saturated, and the concentration of ammonia can be easily obtained.

Furthermore, a temperature sensor 15 for measuring the temperature inside the housing 11 is provided, and the concentration of ammonia is calculated from the amount of change in the measured amount of substance at the temperature per predetermined time based on the temperature measured by the temperature sensor 15. Since the calculation is performed, the change in the amount of substance based on the saturated vapor pressure that changes with temperature can be taken into consideration, and the concentration of ammonia can be accurately obtained.

Furthermore, it is equipped with an atmospheric pressure sensor 16 that measures the atmospheric pressure inside the housing 11, and based on the atmospheric pressure measured by the atmospheric pressure sensor 16, the concentration of ammonia is calculated from the amount of change in the measured amount of substance at the atmospheric pressure per predetermined time. Since the calculation is performed, the change in the amount of substance based on the saturated vapor pressure that changes according to the atmospheric pressure can be taken into consideration, and the concentration of ammonia can be accurately obtained.

In the above embodiment, the measurement of the ammonia concentration in the eel farm has been described as an example, but the concentration of other substances may be measured as well as the concentration of ammonia, and the concentration in water may be used. The concentration of the dissolved substance dissolved in any liquid is not limited to the above, and can be calculated by applying the measurement system according to the present embodiment.

(Second Embodiment of the present invention)
The measurement system according to this embodiment will be described with reference to FIG. The measurement system according to the present embodiment is a modification of the measurement system according to the first embodiment, and includes an opening that can be opened and closed in a non-distribution area. In this embodiment, the description overlapping with the first embodiment will be omitted.

FIG. 9 is a diagram showing a structure of a sensor unit of the measurement system according to the present embodiment. What is different from the structure of FIG. 2 in the first embodiment is that openings 17a and 17b that can be opened and closed are provided on two opposing surfaces of the side surface portion of the housing 11 which is a non-distribution region. In the present invention, it is necessary to measure the change in the amount of substance of ammonia per unit time before the inside of the housing 11 becomes saturated. Therefore, for example, when the ammonia concentration in water is high, the volume of the housing 11 increases. If it is small, if the surface area of the upper surface portion 11A is large, the inside of the housing 11 may be saturated in an extremely short time. When the inside of the housing 11 is saturated, the amount of substance of ammonia in the housing 11 does not change any more, so that the concentration in water cannot be determined. In such a case, by opening the openings 17a and 17b above the water surface, the environment inside the housing 11 is initialized to the atmosphere, and the housing starts from the time when the openings 17a and 17b are closed again. By measuring the change in the amount of substance of ammonia in 11, it is possible to measure the ammonia concentration in water again.

As described above, when the openings 17a and 17b are opened, water will infiltrate into the housing 11 unless the openings 17a and 17b are opened above the water surface, as shown in FIG. 4A. This is particularly effective when only a part of the sensor unit 10 is immersed in water.

Further, even if the inside of the housing 11 is not initialized with the atmosphere as in the present embodiment, the state inside the housing 11 changes due to changes in temperature and atmospheric pressure (parameters related to the saturation state), and the changes occur. By changing the ammonia concentration in accordance with the above, it is possible to obtain the ammonia concentration in water from the change in the amount of substance of ammonia in the housing 11 as in the case of the first embodiment.

(Third Embodiment of the present invention)
The measurement system according to this embodiment will be described with reference to FIG. The measurement system according to the present embodiment uses the measurement system according to each of the above-described embodiments, and determines the concentration of the dissolved substance at an arbitrary depth. In this embodiment, the description overlapping with each of the above-described embodiments will be omitted.

FIG. 10 is a diagram showing a structure of a sensor unit of the measurement system according to the present embodiment. The structure of FIG. 2 in the first embodiment and the structure of FIG. 9 in the second embodiment are different from the buoyancy applied to the housing 11 from all sides of the upper surface portion 11A of the housing 11 which is on the lower side at the time of measurement. The point is that a weight 18 having a weight larger than that of the weight 18 is suspended. That is, when the housing 11 is put into water, the housing 11 sinks due to the weight of the weight 18, and when the weight 18 reaches the bottom of the water, the position is fixed to some extent by the weight. Further, the distance between the weight 18 and the housing 11 can be arbitrarily changed, and the ammonia concentration at an arbitrary distance (height) from the bottom of the water can be obtained.

It should be noted that the ammonia concentration at an arbitrary distance (height) from the water surface is obtained by arranging floats having a buoyancy larger than the weight of the weight 18 from all sides of the bottom surface 11c of the housing 11 which is on the upper side at the time of measurement. It is also possible. In this case, since the height of the water surface is used as the reference instead of the bottom of the water, it is possible to measure the stable height even in an environment where the bottom of the water is uneven and unstable. ..

Further, the arithmetic unit 20 may create and output a three-dimensional ammonia concentration map using the information measured at a plurality of positions on a plane and the information measured at a plurality of depths.

As described above, in the measurement system 1 according to the present embodiment, since the weight 18 having a weight larger than the buoyancy when a part or the whole of the housing 11 is submerged in water is provided, the state of being submerged in water is provided. It is possible to obtain the concentration with, and the concentration distribution in the depth direction can be obtained.

1 Measurement system 10 Sensor unit 11 Housing 11A Top surface 11B Side surface 11C Bottom surface 12 Ammonia sensor 13 Transmitter 14 Moisture permeable waterproof sheet 15 Temperature sensor 16 Pressure sensor 17a, 17b Opening 18 Weight 20 Arithmetic unit 21 Arithmetic unit 22 Output Control unit 23 Storage unit 30 Display 210 CPU
220 RAM
230 ROM
240 HD (HARD DISK)
250 communication I / F
260 I / O I / F

Claims (8)

A housing formed of at least a distribution region that enables the flow of gas and a non-distribution region that disables the flow of liquid and gas.
A measurement sensor arranged in the housing and measuring the amount of the dissolved substance contained in the liquid in contact with the distribution region in the housing.
A measurement system including a calculation means for calculating the concentration of the dissolved substance in the liquid based on the information of the amount of the substance measured by the measurement sensor. In the measurement system according to claim 1,
A measurement system in which the calculation means calculates the concentration of the dissolved substance based on the amount of change in the amount of the substance per predetermined time in a state before the amount of the substance of the dissolved substance converges in the housing. In the measurement system according to claim 2,
A storage means for storing a change in the amount of the substance per predetermined time until the amount of the substance of the dissolved substance converges in the housing according to the concentration of the dissolved substance in the liquid is provided.
A measurement system in which the calculation means extracts concentration information of the dissolved substance corresponding to the measured change amount of the substance amount per predetermined time from the storage means. In the measurement system according to claim 2 or 3.
A temperature sensor for measuring the temperature inside the housing is provided.
A measurement system in which the calculation means calculates the concentration of the dissolved substance from the amount of change in the amount of the substance measured at the temperature per predetermined time based on the temperature measured by the temperature sensor. In the measurement system according to any one of claims 2 to 4.
A barometric pressure sensor for measuring the barometric pressure inside the housing is provided.
A measurement system in which the calculation means calculates the concentration of the dissolved substance from the amount of change in the amount of the substance measured at the atmospheric pressure per predetermined time based on the atmospheric pressure measured by the atmospheric pressure sensor. In the measurement system according to any one of claims 1 to 5.
A measurement system including an opening that can be opened and closed in the non-distribution area. In the measurement system according to any one of claims 1 to 6.
A measurement system in which a moisture-permeable waterproof sheet is arranged in the distribution area. In the measurement system according to any one of claims 1 to 7.
A measuring system including a weight having a weight larger than the buoyancy when a part or all of the housing is submerged in the liquid.

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