Since 1998, the PRISM (Puget Sound Regional Synthesis Model) program at University of Washington has conducted semiannual cruises to ~40 stations within the greater Puget Sound basin. The cruises are designed to collect a synoptic snapshot of the oceanographic conditions in Puget Sound in summer and winter.

In 2008, the PMEL Carbon Group was invited by PRISM to join in these semiannual cruises to make inorganic carbon measurements.  In August 2008, the PRISM cruise took place on the EPA Ocean Survey Vessel Bold (currently sailing under the flag of Vanuatu) and occupied the historical suite of PRISM network stations in addition to stations extending through the Strait of Juan de Fuca into the coastal ocean off Washington.  On this cruise, discrete samples were collected for dissolved inorganic carbon (DIC), total alkalinity, and spectrophotometric pH from most CTD bottles collected at the stations.  Underway measurements of air and water pCO₂ were made throughout the cruise with a General Oceanics 8050 system using a showerhead equilibrator for water pCO₂ measurements.  Underway measurements of air and water, DIC, and pH were also made spectrophotometrically using a prototype Multi-parameter Inorganic Carbon Analyzer (MICA).

Data from discrete samples collected on the February and August 2008 PRISM cruises have been published in an article in Estuarine, Coastal, and Shelf Sciences in August 2010 (Feely et al., 2010).  The 8-panel figure on this page shows the major results, with transect profiles for the Main Basin of Puget Sound (left) and Hood Canal (right) of salinity (A, D), oxygen (in micromoles kg^-1, B, E), pH (C, F), and aragonite saturation state (D, G).

References

Feely, R.A., S.R. Alin, J. Newton, C.L. Sabine, M. Warner, C. Krembs, and C. Maloy, 2010. The combined effects of ocean acidification, mixing, and respiration on pH and carbonate saturation in an urbanized estuary. Estuarine, Coast, and Shelf Science, 88: 442-449. [pdf]