1. Lecture 2 - Major Ions in Sea Water What is the composition of seawater? What defines Major Ions? What are their concentrations? What are their properties?

2. How are the major ions of seawater defined? What are the major ions? Elements versus species? moles versus grams – conversions (See E&H Table 1.2)

3. DIC Liverpool and NIO DOM, Si and gases Units cations Na + > Mg 2+ > Ca 2+ > K + >Sr 2+ anions Cl - >> SO 4 2- > HCO 3 - > F - B(OH) 3 

4. Some major ions are conservative. These are Na, K, SO 4, Br, B and F. What does this mean? conservative. How do you demonstrate this? What are the consequences? Do conservative major ions have a constant concentration in the ocean? Law of Constant Proportions (Me/S‰ = constant) The Law breaks down in estuaries, evaporite basins, hydrothermal vents.

5. Some Major Ions are non-conservative Examples: Ca, Mg, Sr, Dissolved Inorganic Carbon

6. Calcium (Ca)  Ca = +0.5% to +1.0% with depth Why?? CaCO 3 (s) = Ca 2+ + CO 3 2- Alkalinity ≈ HCO 3 + 2 CO 3 Predict  Alkalinity  Alkalinity = 2  Ca From N. Atlantic to N. Pacific  Ca = 100 – 130  M  Alk = 120 – 130  M Still an Excess Ca Problem! What is the source? (from de Villiers, 1999) Non-Conservative Major Elements

7. Mid water Ca maximum. Compare with  Alkalinity Could this be due to diffuse source low-temperature hydrothermal input from mod-ocean ridges?

8. Ca correlates with He 3 and Si These are also Hydrothermal Vent Tracers

9. Inverse Mg – Ca Relationship from EPR at 17  S; 113  W (from de Villiers, 1999) Note significant variability in Mg (normalized to S = 35)! In this case ~1% variability. Hydrothermal Origin??

10. Mg Alk East Pacific Rise, from Von Damm et al., (1985) Ca

11. Sr – also increases with depth (~2%) and N. Atl to N. Pac Distributions similar to PO 4 (excellent correlation)

12. Excellent Correlation Sr vs PO 4

13. Acantharia shell and cyst Examples from sediment traps at Bermuda Acantharia are marine planktonic protozoans But why? The mineral phase Celestite (SrSO 4 ) produced by Acantharia protozoa is proposed as the transport phase.

14. Review questions about salinity 1. How is the salinity of seawater defined? Units? (see editorial by Millero (1993)). 2. What techniques have been used to measure the salinity of seawater? Precision? 3. How does salinity vary in the surface ocean? 4. What controls this variability?

15. Density of Seawater σ What is salinity? What are  and σ? What are their units?

16. Annual average surface salinity What processes influence surface salinity? Can salinity be changed away from the surface?

17. Salinity Is salinity making the water column stable? Where and where not?

18. Annual average surface temperature Identify influences of the wind-driven circulation on surface temperature

19. Potential Temperature Identify the influence of the wind-driven circulation. Temperature must be responsible for stratification. But everywhere?

20. Waters will move mostly along surfaces of constant density. Surface density, isopycnal outcrops

21. Evaporation and Precipitation Effects on Surface Salinity

23. Sea Surface Salinity

24. Salinity Cross Section in Altantic Ocean

25. Salinity Cross Section (Pacific Ocean)

26. Paleo-temperature application Sr/Ca in corals decreases with increasing temperature. Application to western Pacific warm pool