ESTUARINE CIRCULATION

 

Puget Sound is a set of linked estuaries – each having their own separate characteristics. The circulation within estuaries is controlled by the properties of the two end-member components (seawater and freshwater).  Of these properties, the two most important for the movement and mixing are temperature and salinity. Together they determine the density of the Puget Sound water, and their variation causes and inhibits the movement within the linked estuaries. One important dissolved constituent whose distribution throughout the sound is influenced by the circulation is dissolved oxygen. It is also considered to be an indicator of the health of the sound.

We plan to sample in locations where low dissolved oxygen in the deep waters has been observed. We will compare the distributions of temperature, salinity and dissolved oxygen to compare and contrast these basins. All of the deep waters within Puget Sound must have entered through Admiralty Inlet. Are there similar T-S-O₂ relationships in these locations? Why or why not? We can also compare the measurements taken during our expedition to data collected recently within Puget Sound.  Is there a similar relationship between dissolved oxygen and T-S  in the two locations? How have they changed with time?

METHODS:

We will use a CTD to measure the properties of the seawater. We will perform titrations to measure the dissolved oxygen and calibrate the dissolved oxygen sensor.

POTENTIAL PROJECTS:

T-S Properties - Compare and contrast the properties within Hood Canal (spatial), use the ORCA mooring and Citizen Monitoring CTD to describe the temporal evolution of the T-S properties over the past six months and compare it to dissolved oxygen.

Stratification - How does it vary within Hood Canal? How does it relate to dissolved oxygen and chlorophyll concentrations. What happens at the sill?

Box model of Hood Canal - What is the residence time of the deep layers of this basin? Can we estimate oxygen utilization rates? Is this consistent with previous years?

Long-Term Variability - How does our data fit into the historical record? Can we relate it to El Nino/La Nina? What about weather (this spring vs. climatology)?