CO2 ADDITION EXPERIMENTAL SYSTEM

System Outline

　The global warming phenomenon which is often heard by news recently occurs because of the CO2(carbon dioxide) in the atmosphere increasing every year. In the same way, CO2 contained in the seawater is also increasing every year. When CO2 melts in water, water quality indicates the acidic character (pH of water becomes lower). Therefore when the amount of the CO2 in a seawater increases, the seawater become acidic, and pH of the seawater will go down.
　It is very important to investigate the effect of the acidification of the seawater which occurs by means of the higher CO2 concentration of the atmosphere on the sea life, for the prediction of the marine ecosystem in the future.
　At this CO2 addition experimental system, Shirahama's seawater is sampled and the CO2 concentration of the seawater is measured, and "seawater of the present CO2 concentration" and "seawater of the future CO2 concentration" are made falsely in the water tank and the life growth experiment is being done at this experiment.
　The CO2 concentration of the seawater changes in the circadian and the seasonal cycle by means of various factors like as a tide, a water temperature, photosynthesis and respiration of the life in the sea. By the results of the continuous measuring of CO2 concentration of the seawater, the CO2 concentration in the water tank is controlled to change to reflect correctly. And then "the present sea" and "the future sea" are controlled experimentally.

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Control Method

(1) Shirahama's seawater is taken up by a pump, and a great deal of seawater and a little air are put in a gas-liquid balancer to mix them and to generate the balanced air that CO2 concentration is same with one of the practical seawater.

(2) This balanced air is led to the CO2 measuring equipment. Moisture contained in "the balanced air" is taken off, and the CO2 concentration is measured by the NDIR method first here. In this way, the CO2 concentration of the seawater (the dissolved CO2 partial pressure) is measured correctly.

(3) According to the "CO2 concentration of the seawater" measured practically, CGM interface direct to prepare "air that CO2 concentration is same with one measured practically" and "the air that CO2 concentration is a little higher than one measured practically" to the control gas generator.

(4) By diluting of 100 % CO2 gas with zero gas generated by the zero gas generator, the control gas generator generates air that CO2 concentration is required.

(5) "seawater of the present CO2 concentration" and "seawater of the future CO2 concentration" are made by addition of these made air to each water tank. By this experiment, we can observe what kind of the influence on the sea life appears when the CO2 concentration of the seawater increases more.

CO2 Measuring Equipment

CO2-2000

　The CO2 concentration is measured by a non-dispersive infrared absorption (NDIR)* method. By measuring the CO2 standard gas several times a day, the more accurate measuring can be done. The CO2 concentration of the ambient air can be measured directly. In contrast, the CO2 concentration of the seawater can be measured by measuring the balanced air throgh the gas-liquid balancer.

●We check and calibrate for 2 kind of standard gas, 300ppm and 750ppm, once a day.

*Non-dispersive infrared absorption (NDIR) method: The CO2 concentration is measured by using a absorption degree of IR (wave length of 4.26 microns) by CO2molecular.

Tandem balancer

Control Gas Generator

CGM-05

　This is to generate gas of the required CO2 concentration by mixing of CO2 high concentration gas and CO2 free gas (zero gas) by the flow control method.

It's possible to generate the 0-400 ppm CO2 gas with 5 L/min. flow rate by using 100% CO2 cylindrical gas.

●By using 2 sets of this control gas generator, we can introduce 2 kinds of air, "the CO2 concentration of the present sea" and "the CO2 concentration of the future sea" to the water tank.

Large-volume Zero Gas Generator

ZGG-05

　It's possible to generate CO2 free gas (zero gas) by 20 L/min. This zero gas is used in the control gas generator.

CGM Interface

CIF-05

According to the CO2 concentration value measured by CO2 analyzer, it is possible to control some sets of control gas generator. And then it is possible to generate the air that CO2 concentration is higher than one measured practically.