Aragonite saturation state dynamics in a coastal upwelling zone

• Main Authors: Harris, Katherine E., DeGrandpre, Michael D., Hales, Burke
• Format: Article in Journal/Newspaper
• Language: English; unknown
• Published: American Geophysical Union
• Subjects: Ocean acidification
• Online Access: https://ir.library.oregonstate.edu/concern/articles/4m90dx12r

Abstract: Coastal upwelling zones may be at enhanced risk from ocean acidification as upwelling brings low aragonite saturation state (Ω[subscript Ar]) waters to the surface that are further suppressed by anthropogenic CO₂. Ω[subscript Ar] was calculated with pH, pCO₂, and salinity-derived alkalinity time series data from autonomous pH and pCO₂ instruments moored on the Oregon shelf and shelf break during different seasons from 2007 to 2011. Surface Ω[subscript Ar] values ranged between 0.66 ± 0.04 and 3.9 ± 0.04 compared to an estimated pre-industrial range of 1.0 ± 0.1 to 4.7 ± 0.1. Upwelling of high-CO₂ water and subsequent removal of CO₂ by phytoplankton imparts a dynamic range to Ω[subscript Ar] from ~1.0 to ~4.0 between spring and autumn. Freshwater input also suppresses saturation states during the spring. Winter Ω[subscript Ar] is less variable than during other seasons and is controlled primarily by mixing of the water column. Keywords: Oregon coast, biogeochemical processes, coastal upwelling, aragonite saturation states