| Summary: | Quadra Island, at the northern terminus of the Salish Sea, has been a site for shore-based direct measurements of sea surface carbon dioxide partial pressure (pCO2) since December 2014. Initially, this effort coupled pCO2 data with total alkalinity estimated using regionally specific empirical relationships to resolve the marine carbonate system. These calculations were validated by comparing calculated pHT with direct pHT measurements made adjacent to the seawater intake every 30 minutes over a near 3-month period. In this way, the annual cycle was resolved at the Quadra Island site, which provided valuable information regarding scales of variability, the principle physical and biological drivers, and the shifting baseline resulting from anthropogenic CO2 invasion. Efforts now have built upon this initial work by implementing a novel analyzer capable of both discrete and continuous direct pCO2 and total CO2 (TCO2) measurements, known as a Burke-O-Lator (Dakunalytics, LLC). Carbonate mineral saturation states are now resolved in real-time at the shore-side facility, and displayed via the Hakai Institute and IOOS Pacific Region Ocean Acidification (IPACOA) data portals. Water column discrete pCO2 and TCO2 measurements are also now made on samples drawn from Niskin bottles deployed during near weekly survey cruises to core oceanographic stations in region. During this talk, results will be discussed in terms of: (1) the carbonate system resolved by direct pCO2 measurements with derived alkalinity, (2) the carbonate system resolved by the Burke-O-Lator pCO2 and TCO2 measurements, and (3) temporal and spatial variability of the carbonate system through the water column at core oceanographic stations.
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