 Instrumentation  CTD  Dissolved Oxygen Sensor  ADCP/ Current Meters  Oxygen Titrations  Nutrient Concentrations Circulation and Chemical Tracer Distribution Physical Oceanography Chemical Oceanography

Units Temperature: °C Salinity: no units; defined by 1978 Practical Salinity Scale (PSU) Pressure: db (decibars) Density Density (ρ) is a function of T, S, and p ρ(4°C, 0, 1 atm) = 1 g cm -3 = 1000 kg m -3 Potential Density of Seawater (corrected for compressibility) ranges from 1022 kg m -3 to 1028 kg m -3 in the open ocean Sigma Theta (σ θ ) = ρ(T, S, 1 atm) [kg m -3 ]

We prefer concentration Units of mol/kg Dissolved Oxygen Units?? Puget Sound Scientific Literature: mg/L, mg-at/L, mL/L, μmol/kg Conversion Factors: 1 mole O 2 = 32 g O 2 = L O 2 = 2 g-at O 1 L seawater = 1000 cm 3 = (0.001 m 3 )×(density of SW) Density of SW [kg/m 3 ] = sigma theta Text

An estuary is... A place where river(s) meet the ocean that has surrounding land and a limited opening... Puget Sound is an estuary; it is connected to the Pacific Ocean through the Straits of Juan de Fuca. Coastal Plain or Drowned River Valley Estuary

–Sill blocks exchange of deep water with ocean  Little water movement below sill depth  Strong vertical stratification Fig 12.35

Solid = Surface Dashed = Deep Schematic Diagram of the Flow in Puget Sound Estuarine Circulation: Surface Outflow, Deep Inflow Driven by river input, mixing, and deep water intrusions Port Susan Saratoga Passage WHIDBEY BASIN Admiralty Inlet

PROCESSES THAT CONTROL CIRCULATION: --Wind Forcing --Density Stratification Freshwater inflow at the surface --Tides --Flushing events from the open ocean

Stratification How does it change from rivers to Main Basin? How does change in stratification affect biology?

Measured Currents are dominated by the tides Estuarine flow revealed only when tides are removed Tides ≈ 5-10 × Strength of Estuarine Flow

Current Meter Measurements in the Main Basin -- Averaged over the interval indicated -- With the Tidal currents removed Level of no motion?

Episodic Intrusions of Deep Water

Numerical Modeling 20 layers 350-m resolution in Puget Sound River flow - 15 major river, USGS Atmosphere - 6-hour avg from MM5 Eight tidal components

Water Residence Times Box Model ( ) Numerical Model (2006)

Cycles of Phosphorus, Nitrogen, Carbon, Oxygen and Silica in Puget Sound waters Tracers of Biological Production and Respiration REDFIELD RATIOS: ∆P : ∆N : ∆C : ∆O 2 1 : 16 : 106 : -153 For diatoms: NO 3 - : Si ratios: ∆N : ∆Si 1 : (1-3)

Dissolved Inorganic Phosphorus, DIP vs Dissolved Inorganic Nitrogen, DIN In the Ocean REDFIELD STOICHIOMETRY OF LIFE: P : N : C : O 2 = 1 : 16 : 106 : 153

Sections of Oxygen, Phosphate, and Nitrate in Whidbey Basin, Oce 220, 2010 O 2 ( μ mol kg -1 ) PO 4 3- ( μ mol kg -1 ) NO 3 - ( μ mol kg -1 )

Nitrate : Phosphate ratios in Port Susan Compilation from recent data (Oce 220, 2010) AOU (Apparent Oxygen Utilization) = [0 2 sat ] –[O 2 ]

RATES: NET OXYGEN PRODUCTION -- PHOTOSYNTHESIS Oxygen Supersaturation in Puget Sound Surface waters Oce ( Percent Supersaturation)

RATES OF NET BIOLOGICAL OXYGEN PRODUCTION = ∆O 2 / ∆C (153/106) X NET CARBON PRODUCTION (NCP) OXYGEN FLUX TO THE ATMOSPHERE ~ NET BIOLOGICAL O 2 PRODUCTION F O2 = - G O2 {[O 2 ]-[O 2 ] sat } {[O 2 ]-[O 2 ] sat } The Gas Exchange Mass Transfer Coefficient, G, is a function of wind speed

Rates of Respiration in Waters Below the Surface Oxygen Utilization Rate (OUR) = Respiration Rate = AOU / t t = time since water was at the surface In Whidbey Basin deep water t = time since water came into the basin from outside RATES: NET O 2 CONSUMPTION-- RESPIRATION

Knudsen’s Equations Water Balance: T in + R = T out Salt Balance: S in T in = S out T out Solve for T out : T out = R×S in /[S in - S out ] Can add temporal variability, mixing between layers

Main Basin