Marine CO.sub.2 system variability along the northeast Pacific Inside Passage determined from an Alaskan ferry

Information on marine CO.sub.2 system variability has been limited along the northeast Pacific Inside Passage despite the region's rich biodiversity, abundant fisheries, and developing aquaculture industry. Beginning in 2017, the Alaska Marine Highway System M/V Columbia has served as a platform for surface underway data collection while conducting twice weekly â¼1600 km transits between Bellingham, Washington, and Skagway, Alaska. Marine CO.sub.2 system patterns were evaluated using measurements made over a 2-year period, which revealed the seasonal cycle as the dominant mode of temporal variability. The amplitude of this signal varied spatially and was modulated by the relative influences of tidal mixing, net community production, and the magnitude and character of freshwater input. Surface water pH.sub.T (total hydrogen ion scale) and aragonite saturation state (Ω.sub.arag) were determined using carbon dioxide partial pressure (pCO.sub.2) data with alkalinity derived from a regional salinity-based relationship, which was evaluated using intervals of discrete seawater samples and underway pH measurements. High-pCO.sub.2, low-pH.sub.T, and corrosive Ω.sub.arag conditions (Ω.sub.arag