2023 Volume 79 Issue 17 Article ID: 23-17190
When estimating the concentration of CO2 in water from the observed variables of DIC, TA, and pH based on the equilibrium relationship of the carbonic acid system, it is necessary to select an appropriate estimation pattern for the target water area from among several estimation patterns based on the combination of observed variables.
In this study, water sampling surveys were conducted in different water areas in Osaka Bay, and the estimation error of each estimation pattern was confirmed by comparing the measured values of CO2 using an originally developed analysis method with the estimated values calculated from observed variables, and the effect of the measurement accuracy of observed variables on the calculation results of CO2 was examined through sensitivity analysis. As a result, we found that the pattern using pH as an observed variable had a smaller error in rivers and estuaries, while the pattern using DIC-TA had a smaller error in ocean areas near the open sea. The comparison of the rate of change of the estimated results in relation to the measurement error of each observed variable revealed that the influence of pH was larger than that of TA and DIC, indicating that special care should be taken in the observation of pH.
