Continuous Time-Series of Carbonate System Dynamics in the Coastal Oregon Upwelling System
Abstract
The increase in atmospheric CO2 concentrations due to anthropogenic CO2 emissions has been somewhat mitigated by the absorption of approximately one third of emitted CO2 into the oceans. Once CO2 dissolves in water, it forms carbonic acid and increases hydrogen ions, thus decreasing seawater pH. In coastal upwelling zones high CO2, low pH water upwells from depth on to the continental shelf. This “acidified” water reduces the saturation states of calcite and aragonite, adversely affecting calcifying organisms. To study the pH dynamics in a coastal upwelling system Submersible Autonomous Moored Instruments for measuring the partial pressure of CO2 (pCO2) (SAMI-CO2) and pH (SAMI-pH) were moored in surface waters off the coast of Oregon at 44° 37.93’ N, 124° 18.19’W in spring of 2009 and from autumn 2009 through summer 2010. In addition, a SAMI-CO2 and a SAMI-pH were moored at a depth of 123 m on the shelf break just west of the surface mooring. Data was collected between autumn 2009 and summer 2010 at this location. The sensors tracked the temporal evolution of waters upwelling to the surface. Oceanographic data collected on the moorings were combined with pH and pCO2 data to calculate saturation states for calcite and aragonite using CO2SYS. The data show that the 2009 summer upwelling season continued into October 2009 (as seen by steep drops in pH and saturation state indicating strong upwelling events). pH throughout the year ranged from 7.8 to 8.4 while pCO2 ranged from below 200 to close to 800 µatm at the surface, and between 300 to 1400 µatm at the continental shelf break. Saturation states in the highly productive surface waters varied significantly between 5.4 to 1.6 for calcite and from 3.4 to below 1 during upwelling events during spring and fall but leveled out during the winter to approximately 3.4 and 2.2, respectively. High temporal resolution datasets of this type are integral to increasing our understanding of the global carbon cycle and the potential effects of ocean acidification on marine organisms.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMOS23A1568H
- Keywords:
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- 4806 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Carbon cycling;
- 4835 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Marine inorganic chemistry