Ocean Acidification

We currently monitor indicators of ocean acidification at two locations: Point Williams and Quartermaster Harbor Yacht Club. These two locations represent deep Central Basin water and a shallow, protected embayment.

High-precision pH sensors (SeaFET V2) collect data every 15 minutes. These pH data are from a single depth near the surface at both locations. Other data, like temperature and salinity, are collected simultaneously as part of our Moorings Program. These additional data are necessary to fully characterize the carbonate system, which is a series of marine chemistry equations that determines how much shell-forming material (carbonate) is available at a given pH.

Once-a-month bottle samples are analyzed for two carbonate system parameters: total alkalinity (a measure of how resistant water is to further acidification) and dissolved inorganic carbon. We use these to calculate aragonite saturation state, which tells us how corrosive the water is. These samples are collected both at the surface and in deeper water.

We use the data we collect to understand day-to-day changes, seasonal changes, and long-term changes to carbon chemistry in Puget Sound. In shallow areas like Quartermaster Harbor, we see larger day-to-day changes in pH compared to deeper areas. It is important for us to understand these changes so we can better estimate exposure to corrosive water.

We expect water in Puget Sound to become more corrosive over timedue to climate change impacts. Our data can tell us the size of those impacts and how it is different between shallow and deep water.