Development and application of in situ analyzer for carbon dioxide in seawater
Guocui Sun, Quanlong Li *
State Key Laboratory of Marine Environmental Science (Xiamen University)
As the world's largest carbon dioxide absorber, the ocean absorbs 25% of the total carbon dioxide emitted by humans each year, it is of great significance for us to further strengthen the monitoring, estimation and research of ocean carbon dioxide systems in order to have a deep understanding of global carbon cycle and grasp the future changes of global climate in a timely manner. The Marine carbon dioxide system is mainly analyzed by four parameters: pH, total alkalinity (TA), dissolved inorganic carbon (DIC) and partial pressure of carbon dioxide (pCO2). When two of these parameters are known, the whole system can be determined in combination with temperature and salinity data. Among them, in situ measurement of carbon dioxide is an important means to obtain the information of ocean carbon dioxide cycle and water vapor flux. The on-line carbon dioxide analysis instrument is large in volume, high in power consumption and requires large amount of water, so it needs to be measured on board. In this study, the AF2400 high permeability tube was used as the membrane balancer and li-COR NDIR was used as the detector. The air pump sent the balanced gas in the membrane into the NDIR detector to achieve the determination of carbon dioxide concentration. The instrument has been applied to the in-situ monitoring of carbon dioxide in the water near Furong Lake at Xiamen University's Xiang'an Campus, and the instrument has simple structure, small size, low power consumption and can be placed underwater for a long time.
Keywords：carbon dioxide, marine, in situ analysis
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