- 1) Overview
- a) Describewhatismeantby"residencetime".
- b) Describethedifferencebetweenconservative,nutrient-like,andscavengedelements. Give an example of each, and compare how their residence times differ.
- 2) Redfield Stoichiometry
- a) Thecompositionofseawaterhasbeenarguedtobetheendproductofanintricate interweaving of physical, chemical and biological processes. Carefully draw a vertical profile of dissolved oxygen in the North Pacific (include approximate units on axis). Label major physical features of the water column. Explain the major physical, chemical, and biological processes that lead to the profile that you've drawn.
- b) Now draw a vertical profile for nitrate in the North Pacific (again label and include units on axis). Explain what is meant by the term "Redfield stoichiometry", and the standard "Redfield ratio". How is this stoichiometry manifested in the vertical distributions of dissolved oxygen and inorganic fixed nitrogen you just drew?
- c) Finally,(withadashedline)addverticalprofilesfortheNorthAtlanticOceanand explain why the profiles look different in this ocean basin.
- d) Discuss briefly the limitations of the standard Redfield ratio.
- 3) Carbonate Buffer System
- a) CarefullydrawatypicalverticalprofileforpHintheNorthPacific.Labelandput units on axes. Explain what factors control the pH of seawater and describe the factors responsible for its variation with depth.
- b) With a scale change, what two other chemical species would have similar profiles? Explain why these three profiles are similar.
- c) UseadashedlinetodrawwhatyouthinkapHprofilefortheNorthAtlanticwould look like. Briefly explain the difference (if any).
4) Stable isotopes
To what type of oceanographic region would you go to find the maximum possible
isotopic fractionation of δ15N from the uptake of NO3- during photosynthesis? Where would you expect to find no isotopic fractionation of δ15N from the uptake of NO3- during photosynthesis? Explain why.