JPH05232103A - Method for measuring partial pressure of carbon dioxde dissoved in water quickly and accurately - Google Patents

Method for measuring partial pressure of carbon dioxde dissoved in water quickly and accurately

Info

Publication number
JPH05232103A
JPH05232103A JP8135792A JP8135792A JPH05232103A JP H05232103 A JPH05232103 A JP H05232103A JP 8135792 A JP8135792 A JP 8135792A JP 8135792 A JP8135792 A JP 8135792A JP H05232103 A JPH05232103 A JP H05232103A
Authority
JP
Japan
Prior art keywords
carbon dioxide
water
gas
air
concentration
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP8135792A
Other languages
Japanese (ja)
Inventor
Fukuichi Fujiwara
福一 藤原
Eiji Otaki
英治 大滝
Eiji Yamashita
栄次 山下
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to JP8135792A priority Critical patent/JPH05232103A/en
Publication of JPH05232103A publication Critical patent/JPH05232103A/en
Pending legal-status Critical Current

Links

Landscapes

  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

PURPOSE:To make it possible to measure the partial pressure of carbon dioxide in water with a small amount of sample water by replacing the carbon dioxide dissolved into the water with the carbon dioxide in gas, and obtaining the concentration of the carbon dioxide in introduced gas, wherein the change in concentration of the carbon dioxide in the gas that is exhausted through an exhaust port is not present. CONSTITUTION:Air in a container 5 is gradually displaced with from a gas cylinder 1. The air, which has passed through the container 5, passes through a dryer 6 from an exhaust port 5c and passes through a measuring cell 7a of a carbon-dioxide-concentration measuring device 7. Then, the air is discharged into atmosphere. The concentration, which is measured with the measuring device 7, is recorded in a recorder 8. The air from the air cylinder 1 is made to flow until the concentration, of the carbon dioxide in the discharged gas and that in the air in the cylinder 1 become equal. When a three-way cock 4 is set at a liquid side 4b, the air becomes bubbles so as to pass in the water. The bubbles disappear at the surface of liquid. The air passes through an air flowout port 5c and the dryer 6. The air is discharged into atmosphere after passing the measuring cell 7a. The sample water is discharged at every one time, and the sample water is replaced. The cylinder 1 is used, and the operation is repeated.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【発明の目的】水に溶解した二酸化炭素の分圧を、少量
の水を用いて、迅速、かつ、誤差の少ない方法で測定す
る。
It is an object of the present invention to measure the partial pressure of carbon dioxide dissolved in water with a small amount of water in a rapid and error-free manner.

【0002】[0002]

【産業上の利用分野】本発明は、水中に溶解した二酸化
炭素の分圧を測定する方法に関する。
FIELD OF THE INVENTION The present invention relates to a method for measuring the partial pressure of carbon dioxide dissolved in water.

【0003】[0003]

【従来の技術】従来の、水に溶解した二酸化炭素分圧の
測定方法は、例えば、気象庁発行の「海洋観測指針」に
ある、図4のような構成をとった方法が知られている。
この例では、試料を液ポンプ3によって加圧、供給し
て、平衡器1の上部にあるスプレー2から、平衡器の内
に噴霧する。スプレーには、絶えず試料が供給されてい
る。平衡器の内で、水に溶解した二酸化炭素と、平衡器
の内の、空気中の二酸化炭素との間でガス交換が起き
る。スプレーを用いるのは、気液の接触面積を大きくし
て、ガス交換を促進するとともに、気液内の二酸化炭素
の拡散を助長するためである。霧状になった水は、平衡
器の内を通過した後、底に溜り、排水口から排水され
る。一方、ガス系は閉回路になっていて、外の空気が入
らないように考慮されている。この回路内には、平衡器
1、非分散赤外吸収型二酸化炭素濃度測定器6の測定セ
ル6a、乾燥器5、ガスポンプ4が接続されている。ガ
ス回路の内の、一定容積の空気は、水と逆方向に、ガス
ポンプによって循環させられる。平衡器の内に水を噴霧
しながら、ガスを循環させると、二酸化炭素濃度測定器
6で連続測定している、ガス回路内の二酸化炭素の濃度
が変化する。これは、空気中の二酸化炭素と、水中の二
酸化炭素がガス交換して、空気中の二酸化炭素が水中に
溶解したか、または、水中の二酸化炭素が空気中に放出
されたかを示している。平衡器の内の空気中の二酸化炭
素の分圧が、水中の二酸化炭素分圧より大きいとき、空
気中の二酸化炭素濃度は減少して、逆の場合は空気中の
二酸化炭素濃度は増加する。水中と、空気中に含まれる
二酸化炭素の分圧は、二酸化炭素が水に溶解するか放出
するかを決定して、また、その速度と量を決定する因子
である。
2. Description of the Related Art As a conventional method for measuring the partial pressure of carbon dioxide dissolved in water, there is known a method having a structure as shown in FIG. 4 in the "Ocean Observation Guideline" issued by the Meteorological Agency.
In this example, the sample is pressurized and supplied by the liquid pump 3 and sprayed into the equilibrium from the spray 2 on the upper part of the equilibrium 1. The spray is constantly being supplied with sample. In the equilibrium, gas exchange takes place between carbon dioxide dissolved in water and carbon dioxide in the air in the equilibrium. The reason for using the spray is to increase the contact area of gas-liquid, promote gas exchange, and promote diffusion of carbon dioxide in the gas-liquid. The atomized water passes through the inside of the balancer, then collects at the bottom and is drained from the drain port. On the other hand, the gas system has a closed circuit, and is designed so that outside air does not enter. In this circuit, a balancer 1, a measuring cell 6a of a non-dispersive infrared absorption type carbon dioxide concentration measuring device 6, a dryer 5, and a gas pump 4 are connected. A volume of air in the gas circuit is circulated by the gas pump in the opposite direction to the water. When the gas is circulated while spraying water into the balancer, the concentration of carbon dioxide in the gas circuit, which is continuously measured by the carbon dioxide concentration measuring device 6, changes. This indicates whether carbon dioxide in the air and carbon dioxide in the water are gas-exchanged to dissolve carbon dioxide in the air into the water or carbon dioxide in the water is released into the air. When the partial pressure of carbon dioxide in the air in the equilibrium is higher than the partial pressure of carbon dioxide in water, the carbon dioxide concentration in air decreases, and vice versa. The partial pressure of carbon dioxide contained in water and in the air is a factor that determines whether carbon dioxide dissolves in or releases water and also its rate and amount.

【0004】水中の二酸化炭素分圧の概念について、こ
れまでに得られている知見は、次のとおりである。二酸
化炭素が水に溶解すると、物理的に水に溶解した二酸化
炭素分子のほか、炭酸イオン、炭酸水素イオンを生成す
る。これらのイオンは、速やかに二酸化炭素分子と化学
的に安定な平衡に達する。水素イオン濃度や温度などが
変化すると、二酸化炭素分子の濃度と、これらのイオン
濃度は変化する。イオンは、二酸化炭素分子となったと
き、始めて、ガス交換をして、直接に、イオンと気相中
の二酸化炭素とは、ガス交換をしない。従って、二酸化
炭素分圧は、イオン濃度とは関連がない。イオン濃度と
関連がないので、pHが低く、したがって、これらのイ
オン濃度も低い雨水中や、pHが高い海水について、同
じ方法で測定できる。気液の界面では、液相中に溶解し
ている二酸化炭素分子と、気相中の二酸化炭素分子は、
常に液相から気相、気相から液相へと移動している。数
1に示すように、移動する量は、輸送速度と、液相中と
気相中の分圧差で決まる。気相と液相が平衡であると
き、水中、すなわち液相中の二酸化炭素分圧と気相中の
二酸化炭素分圧との間には、数2が成立する。ここで、
Pwは、一般に液相中の二酸化炭素分圧と呼ばれる、液
相中の二酸化炭素が持つ、物理化学的なポテンシャルで
あって、気体と液体の接している界面にあっては、液相
から気相に移動しようとするポテンシャルである。Pa
は気相中の二酸化炭素分圧であって、気相の圧力が一定
のときは、気相内のガス濃度に比例する。分子の移動で
みると、数2が成立するときは、二酸化炭素の、界面に
おける両相への相互の移動量が、等しい状態とも言え
る。平衡であるとき、液相中の二酸化炭素濃度は、ヘン
リーの法則から、気相中の二酸化炭素分圧で決まる。温
度が一定であるときは、液相中の分圧と濃度は比例する
が、液相中の二酸化炭素濃度が一定であっても、温度が
変化するとき、分圧は変化する。以上述べたように、二
酸化炭素分圧は、温度と濃度の関数であるが、気相と液
相の温度が同一、かつ、一定の温度であって、液相中の
二酸化炭素濃度が変化しなければ、液相中の二酸化炭素
と平衡にある、気相中の二酸化炭素分圧を測定すること
によって、液相中の二酸化炭素分圧が測定できる。
The knowledge obtained so far regarding the concept of carbon dioxide partial pressure in water is as follows. When carbon dioxide is dissolved in water, in addition to carbon dioxide molecules physically dissolved in water, carbonate ions and hydrogen carbonate ions are generated. These ions quickly reach a chemically stable equilibrium with the carbon dioxide molecule. When the hydrogen ion concentration or temperature changes, the concentration of carbon dioxide molecules and the concentration of these ions change. When an ion becomes a carbon dioxide molecule, it first exchanges gas, and does not directly exchange gas with carbon dioxide in the gas phase. Therefore, carbon dioxide partial pressure is not related to ion concentration. Since it is not related to the ion concentration, the pH is low, and therefore, rainwater having a low ion concentration and seawater having a high pH can be measured by the same method. At the gas-liquid interface, the carbon dioxide molecules dissolved in the liquid phase and the carbon dioxide molecules in the gas phase are
It constantly moves from the liquid phase to the gas phase and from the gas phase to the liquid phase. As shown in Expression 1, the amount of movement is determined by the transport speed and the partial pressure difference between the liquid phase and the gas phase. When the vapor phase and the liquid phase are in equilibrium, Formula 2 holds between water, that is, between the carbon dioxide partial pressure in the liquid phase and the carbon dioxide partial pressure in the gas phase. here,
Pw is the physicochemical potential of carbon dioxide in the liquid phase, which is generally called the carbon dioxide partial pressure in the liquid phase. At the interface where gas and liquid are in contact, Pw is the gas from the liquid phase. It is the potential to move to the phase. Pa
Is the partial pressure of carbon dioxide in the vapor phase, and is proportional to the gas concentration in the vapor phase when the pressure in the vapor phase is constant. From the viewpoint of molecular movement, when Equation 2 holds, it can be said that the mutual movement amount of carbon dioxide to both phases at the interface is equal. At equilibrium, the carbon dioxide concentration in the liquid phase is determined by Henry's law from the carbon dioxide partial pressure in the gas phase. When the temperature is constant, the partial pressure in the liquid phase is proportional to the concentration, but even if the carbon dioxide concentration in the liquid phase is constant, the partial pressure changes when the temperature changes. As described above, the carbon dioxide partial pressure is a function of temperature and concentration, but the gas phase and liquid phase temperatures are the same and constant, and the carbon dioxide concentration in the liquid phase changes. If not, the carbon dioxide partial pressure in the liquid phase can be measured by measuring the carbon dioxide partial pressure in the gas phase, which is in equilibrium with the carbon dioxide in the liquid phase.

【0005】[0005]

【数1】 [Equation 1]

【0006】[0006]

【数2】 [Equation 2]

【0007】温度を一定に保ちながら、連続して空気を
循環して、水を噴霧すると、回路内の空気中の二酸化炭
素濃度は、変化して徐々に一定となって、10分から2
5分で空気中の二酸化炭素濃度は一定になる。空気中の
二酸化炭素濃度が一定になったとき、濃度をそのときの
圧力で補正して、分圧を求めて、水中の二酸化炭素分圧
であるとしていた。
When the air is continuously circulated and the water is sprayed while keeping the temperature constant, the carbon dioxide concentration in the air in the circuit changes and becomes gradually constant, from 10 minutes to 2 minutes.
The carbon dioxide concentration in the air becomes constant in 5 minutes. When the concentration of carbon dioxide in the air became constant, the concentration was corrected by the pressure at that time, the partial pressure was calculated, and the partial pressure of carbon dioxide in water was used.

【0008】[0008]

【発明が解決しようとする課題】ところで、水中の二酸
化炭素分圧と、空気中の二酸化炭素分圧が平衡になると
される、25分後にも空気中の二酸化炭素濃度が、僅か
ずつではあるが、変化していることがわかった。このた
め、空気中の二酸化炭素と平衡になったか否かの判定
が、極めて困難であるという問題があった。さらに、連
続して水を噴霧するため、100cc/分以上の流速
で、少なくとも、10分から25分の間、水を流し続け
る必要があるから、多量の水が必要であるという問題も
あった。
By the way, it is said that the partial pressure of carbon dioxide in water and the partial pressure of carbon dioxide in air are in equilibrium. Even after 25 minutes, the concentration of carbon dioxide in air is little by little. , It turned out to be changing. Therefore, there is a problem that it is extremely difficult to determine whether or not the carbon dioxide in the air is in equilibrium. Further, since water is continuously sprayed, it is necessary to keep the water flowing at a flow rate of 100 cc / min or more for at least 10 to 25 minutes, which causes a problem that a large amount of water is required.

【0009】平衡になったか否かの判定が、困難である
ことには、大きな3つの原因があることがわかった。ま
ず第1に、構成上の問題点として、図4の構成では、空
気の回路は外部と遮断されていないと平衡になることは
できない。しかし、排水口から、連続的に水が排水され
ず、水が平衡器の底に溜ってきて、水が溜ってくると、
空気の圧力が徐々に増加して、ある量の水が溜った後、
一度に水が出て行った。この現象は、空気の測定系を、
閉回路に近づけようとして、排水口を小さくしているた
めに起こった。この結果、間欠的に水が平衡器の外に出
て、同時に空気が泡となって出た。その直後、平衡器の
内部は負圧となって、外部の空気が排水口から混入し
た。このことは空気回路を閉回路とすることが非常に困
難であることを示した。第2に、測定時間が長くかかる
問題があった。見かけ上、平衡になるために要する時間
を知るために、二酸化炭素濃度の見かけ上の変化が、ほ
ぼ見られなくなる時間を測ったところ、ほぼ1時間であ
った。しかし、長い時間、試料中の二酸化炭素濃度を一
定に保つことは、極めて困難であるから、試料中の二酸
化炭素分圧が変化し、空気中の二酸化炭素分圧と等しく
なったため、変化がなくなったのかも知れないという疑
問があった。試料の二酸化炭素分圧は、温度が変化しな
くても、試料中のプランクトンの光合成や呼吸、有機炭
素化合物の分解、水素イオン濃度の変化などの他の原因
によって、二酸化炭素濃度が変化するため、変化するこ
とがわかった。このため、海水や河川水、雨水の二酸化
炭素分圧を測定するには、迅速でなければならない。海
水試料を使って、経時変化を測定したところ、その大き
さは、1時間では、冬期で2から5μatm、夏期で5
から30μatmであった。したがって、従来の方法
で、長い時間、測定を続けることはできないことがわか
った。第3に、二酸化炭素濃度測定器は、検出器内の圧
力変化によって、その指示値が大きく変化するため、空
気の回路は圧力を一定に保つことが必要であった。とこ
ろが、図4の構成では、空気の回路中のガスポンプ4で
ガスを循環させているため、圧力を一定に保つことはで
きないことがわかった。
It has been found that there are three major reasons why it is difficult to determine whether or not equilibrium is achieved. First, as a structural problem, in the structure of FIG. 4, the air circuit cannot be in equilibrium unless it is disconnected from the outside. However, if water is not continuously drained from the drain port and water collects at the bottom of the balancer,
After the air pressure gradually increases and a certain amount of water accumulates,
The water went out all at once. This phenomenon is due to the air measurement system,
It happened because the drainage outlet was getting smaller to get closer to the closed circuit. As a result, water intermittently came out of the equilibrium and at the same time air came out as bubbles. Immediately after that, the inside of the balancer became a negative pressure, and the outside air was mixed in from the drain port. This shows that it is very difficult to make the air circuit a closed circuit. Secondly, there is a problem that the measurement time is long. Apparently, in order to know the time required to reach equilibrium, the time when almost no apparent change in carbon dioxide concentration was observed was measured, and it was about 1 hour. However, it is extremely difficult to keep the carbon dioxide concentration in the sample constant for a long time, so the carbon dioxide partial pressure in the sample changed and became equal to the carbon dioxide partial pressure in air, so there was no change. There was a doubt that it might have been. Even if the temperature does not change, the carbon dioxide partial pressure of the sample changes because the carbon dioxide concentration changes due to other factors such as photosynthesis and respiration of plankton in the sample, decomposition of organic carbon compounds, and changes in hydrogen ion concentration. , It turned out to change. For this reason, measuring the carbon dioxide partial pressure of seawater, river water, and rainwater must be rapid. Using seawater samples, we measured changes over time and found that the size was 2 to 5 μatm in winter and 5 in summer in 1 hour.
To 30 μatm. Therefore, it was found that the conventional method cannot continue the measurement for a long time. Thirdly, in the carbon dioxide concentration measuring instrument, the indicated value of the carbon dioxide concentration measuring instrument greatly changes depending on the pressure variation in the detector, and therefore the air circuit needs to keep the pressure constant. However, in the configuration of FIG. 4, it was found that the pressure cannot be kept constant because the gas is circulated by the gas pump 4 in the air circuit.

【0010】試料が多量に必要であることには、以下の
理由で問題があった。即ち、深さ数千mの深海で採取し
た試料は、試料のサンプリングに、多大な努力を要して
いるので、貴重である。また、二酸化炭素濃度が変化し
ないよう処理されて、外国から運ばれる試料や、国内で
あっても山間部などで採取される試料については、輸送
経費の面からみても貴重である。したがって、より少量
の試料で測定できる測定法であることが望まれた。
The large amount of sample required was problematic for the following reasons. That is, a sample collected in the deep sea with a depth of several thousand meters is valuable because a great deal of effort is required for sampling the sample. Also, from the viewpoint of transportation costs, samples that are processed from foreign countries and transported from abroad, or samples that are collected domestically or in mountainous areas are valuable. Therefore, it was desired to have a measuring method that can measure with a smaller amount of sample.

【0011】本発明の目的は上記のような問題点を解消
し、少量の試料と、濃度の異なる二酸化炭素ガスを含む
難溶性のガスを用いて、より迅速、かつ正確に水中の二
酸化炭素分圧を測定できる方法を提供しようとするもの
である。
The object of the present invention is to solve the above-mentioned problems and to use a small amount of sample and a sparingly soluble gas containing carbon dioxide gas having different concentrations to more rapidly and accurately analyze the carbon dioxide content in water. It seeks to provide a method by which pressure can be measured.

【0012】[0012]

【課題を解決するための手段】上記目的を達成するため
に本発明は、水の導入口と排出口、および、ガスの導入
口と排出口を設けた、密閉容器内に、水の導入口から、
溶解した二酸化炭素の分圧を測定しようとする試料水を
入れて、水に接触しない、容器内の高い位置に設けたガ
スの導入口から、一定濃度の二酸化炭素を含む、水に難
溶性のガスを導入して、容器のガス排出口から排出され
るガス中の二酸化炭素濃度を、二酸化炭素濃度計で測定
して、ガスの排出口から排出されるガス中の二酸化炭素
濃度が、ガス中の二酸化炭素濃度と同じ濃度になった
後、ガスを水中に放出する目的で、低い位置に設けた、
別のガス導入口から、ガスを水中に放出して、水に溶解
した二酸化炭素を、ガス中の二酸化炭素と交換させ、排
出口から排出されるガス中の二酸化炭素濃度変化の、極
大、または極小から、変化のない、導入ガス中の二酸化
炭素濃度を求めることによって、水に溶解した二酸化炭
素の分圧を知ろうとするものである。本発明は、空気の
二酸化炭素の分圧と、水の中の二酸化炭素の分圧とを、
少量の試料で、迅速に、水の中の二酸化炭素の分圧が測
定できることを主要な特徴とする。
In order to achieve the above-mentioned object, the present invention provides a water inlet in a closed container provided with a water inlet and a water outlet and a gas inlet and a gas outlet. From
Put the sample water to measure the partial pressure of the dissolved carbon dioxide, do not come into contact with water, from the gas inlet provided at a high position in the container, containing carbon dioxide of a certain concentration, sparingly soluble in water After introducing the gas, measure the carbon dioxide concentration in the gas discharged from the gas outlet of the container with a carbon dioxide concentration meter, and confirm that the carbon dioxide concentration in the gas discharged from the gas outlet is It was installed at a low position for the purpose of releasing gas into the water after reaching the same concentration as the carbon dioxide concentration of
The gas is discharged into water from another gas inlet, carbon dioxide dissolved in the water is exchanged with carbon dioxide in the gas, and the maximum change in the carbon dioxide concentration in the gas discharged from the outlet, or It seeks to know the partial pressure of carbon dioxide dissolved in water by obtaining the carbon dioxide concentration in the introduced gas that does not change from the minimum. The present invention, the partial pressure of carbon dioxide in the air, and the partial pressure of carbon dioxide in water,
The main feature is that the partial pressure of carbon dioxide in water can be measured quickly with a small amount of sample.

【0013】[0013]

【実施例】以下、本発明を図面に示す実施例に基づいて
詳細に説明する。図1はこの発明に係る測定装置のブロ
ック図、図2は一定の濃度の二酸化炭素を含む水に難溶
性のガスを水中に流したとき、ガス中の二酸化炭素濃度
の変化の例、図3は二酸化炭素濃度の変化の極大と極小
から、水中の二酸化炭素分圧を測定を求める方法を示し
た図である。これらの図において、本実施例は、ガス流
路の末端が大気に解放されていて、そのため、非分散赤
外吸収型二酸化炭素濃度測定器の検出器内の、圧力変化
を防ぐことができて、一定の濃度のガスで、水中から二
酸化炭素を放出、または水中に二酸化炭素を吸収させた
とき、ガス中の二酸化炭素濃度が異なると、変化の大き
さが異なることを利用して、変化のない、ガス濃度を求
めることによって、水中の二酸化炭素分圧を知ることが
できるようにした、点に特徴を有する。
DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a block diagram of a measuring device according to the present invention, and FIG. 2 is an example of a change in carbon dioxide concentration in gas when a sparingly soluble gas is caused to flow into water containing carbon dioxide at a constant concentration. FIG. 4 is a diagram showing a method for obtaining the measurement of the partial pressure of carbon dioxide in water from the maximum and minimum changes in carbon dioxide concentration. In these figures, in this example, the end of the gas flow path is open to the atmosphere, and therefore, the pressure change in the detector of the non-dispersive infrared absorption type carbon dioxide concentration measuring device can be prevented. , When the carbon dioxide is released from the water or absorbed in the water with a gas of a certain concentration, if the carbon dioxide concentration in the gas is different, the magnitude of the change is different. It is characterized by the fact that the partial pressure of carbon dioxide in water can be known by determining the gas concentration.

【0014】図1において、恒温槽11に試料瓶9と、
容器5が入れてある。これは水中二酸化炭素分圧は、水
温によって大きく変化するので、温度による変化を防ぐ
ためである。乾燥器は、水分によって非分散赤外吸収型
二酸化炭素濃度測定器が妨害されて、誤差が生じるのを
防ぐため、質量流量計3は、流量の変化によって、二酸
化炭素濃度の見かけ上の変化するのを防ぎ、また、流量
によって二酸化炭素濃度の変化の大きさが変動しないよ
う、ガス流量を一定に保つために監視するのが目的であ
る。試料瓶9の中の試料水を、液送ポンプ10で移送し
て、三方コック12を通して容器5の中に入れる。試料
水の量は、排水口の高さで、10ccから15ccの間
で一定量になるように調節する。水中の二酸化炭素を放
出させたり、水中に二酸化炭素を吸収させるためのガス
として、濃度の異なった5本の既知濃度の二酸化炭素を
含む、空気ボンベを用いる。まず、このうちの1本をコ
ック2に接続してコック2を開ける。二酸化炭素を含む
空気は質量流量計3を通って、三方コック4に達する。
質量流量計で測定される流量は、レコーダー8で連続記
録される。質量流量計の指示値は100cc/分から2
00cc/分の間で一定に保つ。三方コック4を空気側
4aに設定しておいて、容器5の空気導入口5aから、
二酸化炭素を含む空気を容器5に入れる。容器5内の空
気は徐々にボンベからの空気で置換されてくる。容器を
通過した空気は、排出口5cから乾燥器6を通って、二
酸化炭素濃度測定器7の測定セル7aを通過した後、大
気中に排出される。容器内の二酸化炭素濃度は二酸化炭
素濃度測定器7で連続的に測定して、その濃度はレコー
ダー8で記録される。二酸化炭素濃度測定器7は、測定
精度を向上させるために、比較セル7bに、既知濃度の
標準二酸化炭素を流して、測定セル内を流れるガスの二
酸化炭素との差を検出できるようになっている。こうす
ることによって、二酸化炭素濃度の変化を、0.1pp
mまで検出することができる。排出されるガスと、ボン
ベ内の空気中の二酸化炭素濃度とが等しくなるまで空気
ボンベの空気を流す。次に、三方コック4を液側4bに
設定する。すると、空気は水中で泡になって、水中を通
過し、その後、泡は液表面で消失して、空気は、空気出
口5cから乾燥器6を通って、二酸化炭素濃度測定器7
の測定セル7aを通過した後、大気中に放出される。上
に述べた操作を、1回毎に試料水を排出して、新しい試
料水を通過させて容器内を洗浄して、試料水を入れ換え
て、別の4本の既知濃度の二酸化炭素を含む空気ボンベ
を使って繰り返す。
In FIG. 1, a sample bottle 9 is placed in a thermostatic chamber 11,
Container 5 is included. This is because the carbon dioxide partial pressure in water largely changes depending on the water temperature, so that the change due to temperature is prevented. In the dryer, the moisture prevents the non-dispersion infrared absorption type carbon dioxide concentration measuring device from interfering with the error, so that the mass flowmeter 3 apparently changes the carbon dioxide concentration depending on the change of the flow rate. The purpose is to monitor the gas flow rate in order to prevent it from happening and to keep the gas flow rate constant so that the magnitude of the change in the carbon dioxide concentration does not change depending on the flow rate. The sample water in the sample bottle 9 is transferred by the liquid feed pump 10 and put into the container 5 through the three-way cock 12. The amount of sample water is adjusted at the height of the drain port so as to be a constant amount between 10 cc and 15 cc. As a gas for releasing carbon dioxide in water or absorbing carbon dioxide in water, an air cylinder containing five carbon dioxide of known concentrations having different concentrations is used. First, one of them is connected to the cock 2 to open the cock 2. The air containing carbon dioxide passes through the mass flow meter 3 and reaches the three-way cock 4.
The flow rate measured by the mass flow meter is continuously recorded by the recorder 8. Mass flow meter reading is from 100 cc / min to 2
Keep constant between 00 cc / min. The three-way cock 4 is set on the air side 4a, and from the air introduction port 5a of the container 5,
Air containing carbon dioxide is placed in the container 5. The air in the container 5 is gradually replaced by the air from the cylinder. The air that has passed through the container passes through the outlet 5c, the dryer 6 and the measurement cell 7a of the carbon dioxide concentration measuring device 7, and then is discharged into the atmosphere. The carbon dioxide concentration in the container is continuously measured by the carbon dioxide concentration measuring device 7, and the concentration is recorded by the recorder 8. In order to improve the measurement accuracy, the carbon dioxide concentration measuring device 7 can detect the difference between the carbon dioxide of the gas flowing in the measuring cell by flowing the standard carbon dioxide of known concentration into the comparison cell 7b. There is. By doing so, the change in carbon dioxide concentration can be reduced by 0.1 pp.
It is possible to detect up to m. The air in the air cylinder is allowed to flow until the discharged gas and the carbon dioxide concentration in the air inside the cylinder become equal. Next, the three-way cock 4 is set on the liquid side 4b. Then, the air becomes bubbles in the water and passes through the water, and thereafter the bubbles disappear on the liquid surface, and the air passes from the air outlet 5c through the dryer 6 to the carbon dioxide concentration measuring device 7
After passing through the measuring cell 7a, the gas is released into the atmosphere. The operation described above is performed by discharging the sample water each time, passing a new sample water to wash the inside of the container, replacing the sample water, and containing another four carbon dioxide of known concentrations. Repeat using an air cylinder.

【0015】図2は、ガスが二酸化炭素濃度測定器の測
定セルを通過する時、レコーダー8によって記録され
る、二酸化炭素濃度の経時変化である。図1の三方コッ
ク4を空気側4aにして、容器内と乾燥器、測定セル内
の空気を、ボンベからの空気で置換すると、約2分後に
は置換されて、ボンベ内の空気と同じ二酸化炭素濃度と
なった。次に、三方コック4を液側4bに切り換えた。
すると、二酸化炭素濃度は、約10秒後に極大、または
極小を示した後、ゆっくりと空気ボンベ中の二酸化炭素
濃度に近づいて行った。pHが低い雨水試料のときは早
く、pHが高い海水のときは、非常にゆっくりと空気ボ
ンベ中の二酸化炭素濃度に近づいた。同一の試料水につ
いて、空気ボンベを変えて、経時変化を示したが、ボン
ベ中の二酸化炭素濃度が272ppmのとき、1の経時
変化を示し、294ppm、338ppmのときはそれ
ぞれ、2、3の経時変化を示した。水中の二酸化炭素分
圧が空気中の二酸化炭素分圧と比較して、高いときは、
二酸化炭素が水中から出てきて空気中の二酸化炭素濃度
は高くなり、逆に、水中の二酸化炭素分圧が低いとき
は、水中に二酸化炭素が溶けて、二酸化炭素濃度は低く
なる。水中の二酸化炭素分圧と、ボンベ内から出てきた
空気中の二酸化炭素分圧が、等しいときは変化しない。
FIG. 2 is a change with time of the carbon dioxide concentration recorded by the recorder 8 as the gas passes through the measuring cell of the carbon dioxide concentration measuring device. When the three-way cock 4 in FIG. 1 is set to the air side 4a and the air in the container, the dryer, and the measurement cell is replaced with air from the cylinder, the air is replaced after about 2 minutes, and the same dioxide as that in the cylinder is replaced. Became the carbon concentration. Next, the three-way cock 4 was switched to the liquid side 4b.
Then, the carbon dioxide concentration reached its maximum or minimum after about 10 seconds and then slowly approached the carbon dioxide concentration in the air cylinder. When the pH of the rainwater sample was low, the concentration was early, and when the pH was high, the concentration of carbon dioxide in the air cylinder approached very slowly. With respect to the same sample water, the time change was shown by changing the air cylinder, but when the carbon dioxide concentration in the cylinder was 272 ppm, it showed a time change of 1, and when the carbon dioxide concentration in the cylinder was 294 ppm and 338 ppm, it showed a few time changes. Showed a change. When the carbon dioxide partial pressure in water is higher than the carbon dioxide partial pressure in air,
When carbon dioxide comes out from water and the carbon dioxide concentration in the air becomes high, on the contrary, when the carbon dioxide partial pressure in the water is low, the carbon dioxide is dissolved in the water and the carbon dioxide concentration becomes low. When the partial pressure of carbon dioxide in water is equal to the partial pressure of carbon dioxide in the air coming out of the cylinder, it does not change.

【0016】図3は、5種の濃度の二酸化炭素を含むに
ついて、水中を通った後の変化が極大になったときの変
化の大きさの違いから、水中の二酸化炭素分圧を求める
方法を示した図である。ボンベから出てきた空気中の二
酸化炭素分圧と、水中の二酸化炭素分圧の差が大きいと
き、変化は大きく、差が少なくなるにしたがって変化は
小さくなってきて、水中の二酸化炭素分圧と、ボンベ内
の空気中の二酸化炭素分圧の差がないとき、二酸化炭素
の水中からの放出量と、水中に溶解する量は等しくなっ
て、変化しない。
FIG. 3 shows a method for obtaining the carbon dioxide partial pressure in water from the difference in the magnitude of the change when the change after passing through the water becomes maximum for the case of containing five concentrations of carbon dioxide. It is the figure shown. When the difference between the partial pressure of carbon dioxide in the air coming out of the cylinder and the partial pressure of carbon dioxide in water is large, the change is large, and the smaller the difference, the smaller the change. , When there is no difference in the partial pressure of carbon dioxide in the air in the cylinder, the amount of carbon dioxide released from water and the amount dissolved in water become equal and do not change.

【0017】図3は、縦軸に変化の最大量、横軸に使用
した空気ボンベ中の二酸化炭素濃度をとったものであ
る。図中の、5点のデータを得るために、試料水の量
は、容器内の洗浄を含めて、約150cc、必要であ
る。測定時間は、1点のデータを得るのに約3分、試料
の交換に要する時間を含めて約20分必要とする。使用
した空気ボンベ中の、二酸化炭素濃度の幅は、約30p
pm毎であって、直線性、再現性とも良好である。水中
の二酸化炭素分圧は、変化の起こらない空気中の二酸化
炭素分圧に等しいから、内挿、または外挿によって、変
化の起こらない濃度を求めることができる。これが水中
の二酸化炭素分圧である。測定値の誤差についてみる
と、内挿によって濃度を求める方が、外挿によるよりも
誤差が小さく、また、空気ボンベ中の、二酸化炭素濃度
の幅を小さくすることによって、測定誤差を小さくする
ことができる。また、直線性、再現性とも良好であるこ
とから、1点のみで水中の二酸化炭素分圧を求めること
は可能であるが、当然に、測定誤差は大きくなる。
In FIG. 3, the vertical axis represents the maximum amount of change and the horizontal axis represents the carbon dioxide concentration in the air cylinder used. In order to obtain the data of 5 points in the figure, the amount of the sample water needs to be about 150 cc including the washing in the container. The measurement time is about 3 minutes to obtain one point of data and about 20 minutes including the time required for exchanging the sample. The width of carbon dioxide concentration in the used air cylinder is about 30p.
The linearity and reproducibility are good for each pm. Since the carbon dioxide partial pressure in water is equal to the carbon dioxide partial pressure in air that does not change, the concentration that does not change can be obtained by interpolation or extrapolation. This is the partial pressure of carbon dioxide in water. Regarding the error in the measured value, it is smaller when the concentration is obtained by interpolation than when it is extrapolated, and the measurement error is made smaller by reducing the width of the carbon dioxide concentration in the air cylinder. You can Further, since the linearity and the reproducibility are good, it is possible to obtain the carbon dioxide partial pressure in water at only one point, but naturally the measurement error becomes large.

【0018】この測定方法の検証のため、次の比較試験
を行った。本発明の測定方法で3回測定した結果、その
二酸化炭素分圧が393±0.5μatmであった海水
中に、二酸化炭素濃度が396ppmの空気を、約6時
間流し続けた。これは、海水中の二酸化炭素分圧が、3
96μatmの海水を得るのが目的である。こうして得
られた試料を、本発明の測定方法で3回測定した結果、
396±0.5μatmであって、本発明の測定方法が
正確であることがわかった。また、得られた試料を従来
の測定法を用いて測定した。従来の測定法では、測定開
始前に、試料中の二酸化炭素分圧を予想していて、試料
中の二酸化炭素分圧に近い分圧を持った空気を、循環空
気として使用する。従来の測定法での、問題点は解決さ
れていないので、ここでは循環空気の濃度変化の様子を
知るのが目的で、平衡に達する時間を知るために、循環
空気中の二酸化炭素分圧は、スプレー開始前は0ppm
とした。測定を開始して数分後には、空気中の二酸化炭
素濃度の大きな変化は見られなくなって、10分後には
約370ppmになった。その後1時間経過後も、僅か
ずつ二酸化炭素濃度は上昇した。この経時変化は、図2
で示したように、一定濃度の二酸化炭素を含むガスを海
水中に流したときの、海水中の二酸化炭素分圧の経時変
化と同様に、循環空気中の二酸化炭素分圧は、ゆっくり
と、海水中の二酸化炭素分圧に近づくことを示した。
The following comparative tests were conducted to verify this measuring method. As a result of measuring three times by the measuring method of the present invention, the carbon dioxide concentration was 393 ± 0.5 μatm, and the air having a carbon dioxide concentration of 396 ppm was continuously flowed for about 6 hours into the seawater. This is because the partial pressure of carbon dioxide in seawater is 3
The purpose is to obtain 96 μatm of seawater. The sample thus obtained was measured three times by the measuring method of the present invention,
It was 396 ± 0.5 µatm, and it was found that the measuring method of the present invention was accurate. Moreover, the obtained sample was measured using the conventional measuring method. In the conventional measurement method, the carbon dioxide partial pressure in the sample is predicted before the measurement is started, and air having a partial pressure close to the carbon dioxide partial pressure in the sample is used as the circulating air. Since the problems with the conventional measurement method have not been solved, the purpose here is to know the state of the concentration change of the circulating air, and in order to know the time to reach equilibrium, the partial pressure of carbon dioxide in the circulating air is , 0 ppm before starting spraying
And A few minutes after the measurement was started, a large change in the carbon dioxide concentration in the air was not seen, and after 10 minutes, it became about 370 ppm. After 1 hour, the carbon dioxide concentration increased little by little. This change over time is shown in FIG.
As shown in, when the gas containing a constant concentration of carbon dioxide is flowed into the seawater, the carbon dioxide partial pressure in the circulating air is slowly changed, similarly to the change with time of the carbon dioxide partial pressure in the seawater. It was shown to approach the partial pressure of carbon dioxide in seawater.

【0019】[0019]

【発明の効果】上記のように本発明では、水中の二酸化
炭素分圧と、空気中の二酸化炭素分圧を平衡にする必要
がないので、従来の測定方法よりも迅速に、より正確に
測定できるようになった。また、少量の試料水で、水中
の二酸化炭素分圧を測定できるようになった。さらにま
た、ガスの回路が大気に解放されているので、非分散赤
外吸収型二酸化炭素濃度測定記録計の、検出器内の圧力
変化によって、その指示値が変化するという短所を避け
ることができて、より正確に二酸化炭素分圧が測定でき
るようになった。
As described above, in the present invention, it is not necessary to equilibrate the partial pressure of carbon dioxide in water and the partial pressure of carbon dioxide in air, so that the measurement can be performed more quickly and more accurately than the conventional measurement method. I can do it. Moreover, it has become possible to measure the carbon dioxide partial pressure in water with a small amount of sample water. Furthermore, since the gas circuit is open to the atmosphere, it is possible to avoid the disadvantage of the non-dispersive infrared absorption type carbon dioxide concentration measurement recorder in which the indicated value changes due to the pressure change in the detector. Now, the carbon dioxide partial pressure can be measured more accurately.

【0020】[0020]

【図面の簡単な説明】[Brief description of drawings]

【図1】本発明の1実施例を示すブロック図FIG. 1 is a block diagram showing an embodiment of the present invention.

【図2】水中に二酸化炭素を含む空気を通したときの、
空気中の二酸化炭素分圧の変化を示した図
[Fig. 2] When passing air containing carbon dioxide into water,
Diagram showing changes in the partial pressure of carbon dioxide in the air

【図3】水中の二酸化炭素分圧を、空気中の二酸化炭素
濃度の変化の割合から内挿して求める方法を示した図
FIG. 3 is a diagram showing a method for interpolating the carbon dioxide partial pressure in water from the rate of change in carbon dioxide concentration in air.

【図4】従来例を示すブロック図FIG. 4 is a block diagram showing a conventional example.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 山下 栄次 岡山県岡山市浦安西町110番地の7 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiji Yamashita 7 at 110 Urayasunishimachi, Okayama City, Okayama Prefecture

Claims (1)

【特許請求の範囲】[Claims] 【請求項1】 水の導入口と排出口、および、ガスの導
入口と排出口を設けた、大気圧に保つことのできる、密
閉容器内に、水の導入口から、溶解した二酸化炭素の分
圧を測定しようとする試料水を入れて、水に接触しな
い、容器内の高い位置に設けたガスの導入口から、一定
濃度の二酸化炭素を含む、水に難溶性のガスを導入し
て、容器のガス排出口から排出されるガス中の二酸化炭
素濃度を、二酸化炭素濃度計で測定して、ガスの排出口
から排出されるガス中の二酸化炭素濃度が、導入ガス中
の二酸化炭素濃度と同じ濃度になった後、ガスを水中に
放出する目的で、低い位置に設けた、別のガス導入口か
ら、ガスを水中に放出して、水に溶解した二酸化炭素
を、ガス中の二酸化炭素と交換させ、排出口から排出さ
れるガス中の二酸化炭素濃度変化の、極大、または極小
から、変化のない、導入ガス中の二酸化炭素濃度を求め
ることによって、水に溶解した二酸化炭素の分圧を知る
ことを特微とする、測定方法。
1. A closed container which is provided with a water inlet and a water outlet and a gas inlet and a gas outlet and which can be maintained at atmospheric pressure, is provided with dissolved carbon dioxide gas from the water inlet. Insert the sample water whose partial pressure is to be measured, and introduce a sparingly soluble gas containing water with a certain concentration of carbon dioxide from the gas inlet provided at a high position in the container that does not come into contact with water. , The carbon dioxide concentration in the gas discharged from the gas outlet of the container is measured with a carbon dioxide concentration meter, and the carbon dioxide concentration in the gas discharged from the gas outlet is the carbon dioxide concentration in the introduced gas. For the purpose of releasing the gas into the water after reaching the same concentration as above, the gas was released into the water from another gas inlet provided at a low position, and the carbon dioxide dissolved in the water was converted into The carbon dioxide concentration in the gas discharged from the outlet after being exchanged with carbon A measuring method characterized by knowing the partial pressure of carbon dioxide dissolved in water by obtaining the carbon dioxide concentration in the introduced gas that does not change from the maximum or minimum change in temperature.
JP8135792A 1992-02-18 1992-02-18 Method for measuring partial pressure of carbon dioxde dissoved in water quickly and accurately Pending JPH05232103A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP8135792A JPH05232103A (en) 1992-02-18 1992-02-18 Method for measuring partial pressure of carbon dioxde dissoved in water quickly and accurately

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP8135792A JPH05232103A (en) 1992-02-18 1992-02-18 Method for measuring partial pressure of carbon dioxde dissoved in water quickly and accurately

Publications (1)

Publication Number Publication Date
JPH05232103A true JPH05232103A (en) 1993-09-07

Family

ID=13744102

Family Applications (1)

Application Number Title Priority Date Filing Date
JP8135792A Pending JPH05232103A (en) 1992-02-18 1992-02-18 Method for measuring partial pressure of carbon dioxde dissoved in water quickly and accurately

Country Status (1)

Country Link
JP (1) JPH05232103A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010241649A (en) * 2009-04-08 2010-10-28 Toshiba Corp Carbon dioxide recovering system
KR101410253B1 (en) * 2012-11-15 2014-06-20 한국해양과학기술원 Apparatus for measuring partial pressure of carbon dioxide within seawater in the water tank
KR20180052908A (en) * 2016-11-11 2018-05-21 한국해양과학기술원 Device for continuous measuring pO2 and pCO2 of aquarium without biofouling on the sensors using air-water equilibrium

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010241649A (en) * 2009-04-08 2010-10-28 Toshiba Corp Carbon dioxide recovering system
KR101410253B1 (en) * 2012-11-15 2014-06-20 한국해양과학기술원 Apparatus for measuring partial pressure of carbon dioxide within seawater in the water tank
KR20180052908A (en) * 2016-11-11 2018-05-21 한국해양과학기술원 Device for continuous measuring pO2 and pCO2 of aquarium without biofouling on the sensors using air-water equilibrium

Similar Documents

Publication Publication Date Title
Gülzow et al. A new method for continuous measurement of methane and carbon dioxide in surface waters using off‐axis integrated cavity output spectroscopy (ICOS): An example from the Baltic Sea
US7029920B2 (en) Method and system for monitoring combustion source emissions
Hales et al. High‐frequency measurement of partial pressure and total concentration of carbon dioxide in seawater using microporous hydrophobic membrane contactors
EP3140645B1 (en) Gas component concentration measurement device and method for gas component concentration measurement
US8077311B1 (en) Spectrophotometric system for simultaneous flow-through measurements of dissolved inorganic carbon, pH and CO2 fugacity
JPS6291861A (en) On-line calibrating apparatus for chemical monitor
Huygen The sampling of sulfur dioxide in air with impregnated filter paper
CN105842725A (en) Method for detecting specific activity of tritiated steam in air
JPH07318555A (en) Total organic carbon meter
Neal Determination of dissolved CO2 in upland streamwater
JPH05232103A (en) Method for measuring partial pressure of carbon dioxde dissoved in water quickly and accurately
Tang et al. A new all‐season passive sampling system for monitoring NO2 in air
CN102008887A (en) Method for testing concentration ratio of slurry in wet flue gas desulfurization absorption tower in thermal power plant
Jongejan et al. An automated field instrument for the determination of acidic gases in air
Buttini et al. Coupling of denuder and ion chromatographic techniques for NO2 trace level determination in air
Almeida et al. Measuring the CO2 flux at the air/water interface in lakes using flow injection analysis
Midgley Investigations into the use of gas-sensing membrane electrodes for the determination of carbon dioxide in power station waters
JP2946800B2 (en) Carbon dioxide measuring device
US4478080A (en) Dewpoint measurement system for near saturation conditions
Kimoto et al. Achieving high time-resolution with a new flow-through type analyzer for total inorganic carbon in seawater
CN211825664U (en) System for survey aquatic methane and carbon dioxide under ordinary pressure
JPH0961361A (en) Continuous ammonia concentration measuring device
CN217084830U (en) Method for measuring gas tracer in water and CO 2 Experimental device for well distribution coefficient
Gallagher et al. Performance of the HPLC/fluorescence SO2 detector during the GASIE instrument intercomparison experiment
US3361661A (en) Apparatus for analyzing gases