1. Lecture 20 “Preformed” Concentrations Lecture 19 – Summary 1) The concentration of any bioactive element can be considered the sum of preformed and remineralized components. 2) For O 2 we can predict the preformed concentration using the temperature-dependent solubility of O 2. The remineralized part is AOU. 3) AOU can be used to distinguish preformed vs remineralized nutrients.

2. Apparent Oxygen Utilization How and why do we define the quantity called AOU?

3. Remineralized PO 4 How is remineralized PO 4 calculated? Why does it increase from Atlantic to Pacific?

4. PO 4 in the Ocean Conveyor

5. “Pre-formed” Phosphate Why does pre-formed PO 4 increase from Atlantic to Pacific? What information does pre-formed PO 4 contain?

6. Why does O 2 increase with depth in the deep ocean more than PO 4 ? 1000 m 2000 m 3000 m 4000 m 0 m

7. 1) Biological pathway consumes oxygen 2) Physical pathway doesn’t… Every PO 4 molecule in the deep ocean got there in 1 of 2 ways: PsPs PdPd “Remineralized Phosphate” “Preformed Phosphate” Revisiting the deep O 2 puzzle

8. Isopycnal surfaces Waters flow into the ocean interior along paths of constant density.

9. Phosphate Distribution Atlantic Pacific The concentration of phosphate in a water parcel can tell us something about remineralization, but only if we know how much PO 4 it started with.