Applications of Autonomous pH and pCO2 Sensors to Study Inorganic Carbon Dynamics in a Coastal Upwelling System

• Main Author: Harris, Katherine Elizabeth
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: University of Montana 2013
• Subjects: sami
• Online Access: https://scholarworks.umt.edu/etd/10867; https://scholarworks.umt.edu/context/etd/article/11914/viewcontent/Harris_umt_0136D_10271.pdf

Submersible Autonomous Moored Instruments for pH and pCO2 (SAMI-pH and SAMI-CO2) were deployed in a coastal upwelling zone on the Oregon Coast to collect unique multi-season, multi-year datasets of carbonate system dynamics. This is the first long-term deployment of the SAMI-pH paired with a SAMI-CO2. The objectives of this study included (1) improving the accuracy of the SAMI-pH (2) assessing the performance of using paired SAMI-pH and SAMI-CO2 measurements to calculate other carbonate system parameters and (3) analyzing the data to better understand the seasonal, inter-annual, and upwelling variation in the coastal marine carbonate system. SAMI-pH accuracy was improved by better characterization of the pH indicator used in these spectrophotometric measurements. Using paired SAMI-pH and SAMI-CO2 measurements from this study to calculate calcium carbonate saturation states (Ω) occasionally induced significant offsets in the results and so should be used with caution. However, a salinity-derived alkalinity for the region was found to calculate more accurate Ω when paired with either SAMI-pH or SAMI-CO2 measurements. This unique, long-term, high temporal resolution dataset (collected over a period of five years) was used to characterize the carbonate system dynamics in this coastal upwelling zone. Large, fast changes in Ω (>3.0) occurred over a period of a few days and aragonite saturation state (ΩAr) decreased to undersaturation (ΩAr