The Chinese Academy of Sciences’ Yantai Institute of Coastal Zone Research (YIC) has created a marine carbon dioxide (CO2) monitoring system based on electrochemical sensing for quick in-situ analysis of dissolved CO2 in seawater, directed by Wei Qin.
An increase in atmospheric CO2 emission due to anthropogenic perturbations can result in a significant rise in CO2 absorption in the ocean. This might lead to a drop in seawater pH and significant changes in the chemical balance of the marine carbonate cycle, all of which could have an impact on marine biota and the ocean environment.
To understand fully the influence of these variations on the marine carbon cycle, high temporal and geographical resolution measurements of dissolved CO2 fluctuation in seawater are required.
In-situ measurements of dissolved CO2 are important because changes in the sample can occur during collection, sample transport and measuring operations owing to re-equilibration between the saltwater sample and the atmospheric CO2.
Probes for seawater parameters (such as pH, temperature, and conductivity), an electrochemical sensing unit based on an ion-selective electrode for specific carbonate detection, autonomous sample analysis, a control system for sensor calibration, salinity impact correction and a flow system for the injection of calibration remedies or saltwater samples make up the monitoring system.
The salinity correction can offer an improved detection accuracy in a high salinity background, making the proposed CO2 monitoring system suitable for marine monitoring.
Wei Qin, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences
Long-term monitoring in three separate marine areas of China - the Bohai Sea, the Yellow Sea and the South China Sea, - was used to assess the working of the dissolved CO2 detection system.
When compared to the reference method (water vapor separation-nondispersive infrared spectroscopy analysis) for real-time monitoring of dissolved CO2 in the Bohai Sea, researchers discovered that this system had a response time of 40 seconds, a reproducibility of 0.3%, and a detection accuracy of 95%.
During the testing period, the monitoring system operated correctly. Its capacity to function independently with procedures for seawater analysis, sensor calibration, data storage and transmission was demonstrated by the obtained results.
Without the need for sample preparation, a submersible monitoring device like this might open up new possibilities for obtaining speedy and precise information about the carbon cycle in marine systems.