高频率分光法测定海水二氧化碳系统参数：需求，研发，和应用 Dr. Zhaohui Aleck Wang Woods Hole Oceanographic Institution, Associate Scientist The marine CO2 (inorganic carbon) system is characterized by four primary parameters – partial pressure of CO2 (pCO2) or CO2 fugacity (fCO2), total dissolved inorganic carbon (DIC), pH, and total alkalinity (TA). These parameters are central to the study of the marine carbon cycle and ocean acidification. There is a high demand for sensors and instruments that can make simultaneous measurements of multiple CO2 parameters, as measurements of at least two parameters are required to fully resolve the carbonate system through CO2 equilibrium calculations. The pair of measured parameters is important to consider since different calculation errors may result from different choices. Measurement frequency is also important to consider depending on the deployment purpose. A new spectrophotometric method has been developed to achieve continuous measurements of DIC and pCO2 in seawater. This method improves the spatiotemporal resolution by more than one order of magnitude compared to the existing spectrophotometric method. The level of precision and accuracy of this method is comparable to that of the existing spectrophotometric method. The characteristics of the new method make it particularly suitable for high-frequency, submerged measurements required for mobile observing platforms in the ocean. Based on the new method, an in-situ sensor has recently been developed for simultaneous measurements of seawater DIC and pH in subsurface marine environments. The sensor is among the first to achieve high-frequency, simultaneous measurements of two CO2 system parameters with sufficient accuracy for use in carbon and ocean acidification studies. Such a capability allows the seawater CO2 system to be fully characterized at high resolution with relatively small errors. Highly productive coastal wetlands are potentially important DIC and TA sources to the ocean globally and regionally. However, current estimates of these fluxes are either highly uncertain or lacking because high resolution measurements are not yet available. The frequency of measurements is critical to determine these fluxes that vary on minute scale. The new high frequency sensor provides a powerful tool to realistically quantify DIC and TA fluxes and study carbonate chemistry in these systems.