Water column CO2 system measurements collected during the 2016 National Oceanic and Atmospheric Administration West Coast Ocean Acidification survey (NOAA WCOA2016) from California to British Columbia

Carbon dioxide partial pressure (pCO2) and total dissolved inorganic carbon (TCO2) measurements were made on seawater collected from 12 depths at select stations occupied during the 2016 National Oceanic and Atmospheric Administration West Coast Ocean Acidification survey (NOAA WCOA2016) from California to British Columbia. NOAA cruise data collected during this survey are available from the National Centers for Environmental Information (https://www.nodc.noaa.gov/ocads/oceans/Coastal/WCOA.html). Hakai Institute staff (Evans) collected data only during the second leg of the survey from May 24 to June 7. Information describing the cruise plan and cruise blog can be found on the NOAA Pacific Marine Environmental Laboratory (PMEL) website (https://www.pmel.noaa.gov/co2/story/2016+West+Coast+Ocean+Acidification+Cruise). Seawater sampling during this cruise was conducted using a conductivity-temperature-depth (CTD) profiler coupled with a 24-Niskin (11-L) bottle rosette. Seawater collection was concentrated in the upper 200 m at standard depths: 3 m, 10 m, 20 m, 30 m, 50 m, 80 m, 100 m, 125 m, 150 m, and 200 m. Two additional deeper depths were sampled when the water column exceeded 200 m. Additional shallow depths were sampled at the Hakai Institute’s oceanographic station QU39 (http://dx.doi.org/10.21966/1.715738). Samples were drawn from the Niskin bottles with care not to introduce bubbles into 350 mL amber glass bottles using silicone tubing, and left with 3 mL of headspace. Samples were then fixed with 200 µL of mercuric chloride and crimp-sealed with polyethylene-lined metal caps. Samples were stored in the dark and at room temperature until analysis on the Hakai Institute’s Burke-o-Lator (BoL). For detailed protocols on data processing including CO2 system determination, and quality assurance, please see Pocock et al. (2017; http://dx.doi.org/10.21966/1.521066). Final CO2 system parameters (pHT, pCO2, and aragonite saturature state) were computed using (primary) CTD temperature and salinity, and BoL determined total CO2 (TCO2) corrected using certified reference materials and alkalinity (Alk) using the carbonic acid dissociation constants of Lueker et al. (2000). Calculations were done relative to in situ pressure. Note Alk here is assumed here to consist of carbonate, bicarbonate, borate, hydroxide, and hydrogen ions; neglecting the influence of nutrients and organic acids. The effort to collect these data are part of the Hakai Institute’s directive to advance the understanding of carbon cycling in northeast Pacific coastal settings with specific emphasis on ocean acidification.