1. The Carbon Cycle

2. Carbon Dioxide and Carbonate system Why is it important? 1. Regulates temperature of the planet 2. Important for life in the ocean 3. Regulates the pH of water

3. 70 ppm

4. TEMPERATURE CO 2 4.5 C

5. CO 2 Temperature 70 ppm

6. CO 2 changes in the last 300 yr 70 ppm Industrial Revolution

7. CO 2 changes in the last 50 yr Oceans Biosphere Rock Weathering

8. How much CO 2 can you sink in the ocean? Process that control CO 2 absorption in the ocean Chemical Biological Physical Carbon Cycle

10. CO 2 O2O2 pH acidbasic

11. Dissolved Gases in the Ocean Oxygen profile low oxygen environment compensation depth Respiration: Animal, plants and microbial decomposition

12. Dissolved Gases in the Ocean Oxygen profile

13. CO 2 O2O2 pH

14. The Carbonate System from dissolution of Calcium Carbonate from dissolved CO 2 gas sources of inorganic carbon Biology and Physics participate in the equilibrium of the carbonate system NOTE:

15. CO 2 in the ocean

16. Total dissolved inorganic carbon this is very small not found in this form Total dissolved inorganic carbon

17. CO 2 O2O2 pH acidbasic

18. Contributes to Higher pH Carbon Dioxide and Carbonate system Contributes to Lower pH - pH + pH

19. Distribution of Carbon species in water + -

20. Control of pH very rapid reaction in seawater at equilibrium Equilibrium constant hydrogen ion concentration

21. + -

22. Why is the pH of seawater close to neutral? seawater pH=7.5-8.5

23. Today‘s world pCO 2 : 280-380 ppmV High-CO 2 world pCO 2 : 580-720 ppmV Emiliania huxleyi Gephyrocapsa oceanica Calcidiscus leptoporus A summary of studies indicate that almost all calcifying species examined to date have shown reduced calcification rates at higher pCO 2 levels, but only a small fraction of the natural species have been tested.

24. Consensus among the participants was that higher CO 2 levels will generally be detrimental to calcifying organisms and that food web structures and biodiversity will likely change, but it is not clear how this might impact overall productivity and top level predators (e.g. fish). CoccolithophoresForams Corals calcite aragonite

26. Warm water corals have primarily formed in aragonite saturation levels > 4, can survive at levels > 3.5, and generally stop growing < 3

28. Carbonate Compensation Depth CCD varies with Latitude CCD varies between Oceans North Pacific: 1000m South Pacific: 2500m Atlantic: 4000m

30. Calcite Compensation Depth Photosynthesis CO 2 + H 2 O  CH 2 O + O 2 Carbon Dioxide Controls Calcite Dissolution and Precipitation CaCO 3 + CO 2 + H 2 O  Ca 2+ + 2HCO 3 -

31. Dissolution Biogenous Particles Carbonates Foraminifera (Calcite) – less soluble Pteropods (Aragonite) – More soluble –Dissolution is highest in Deep Waters High pressure Low temperatures Low pH (high C0 2 ) Carbonate Compensation Depth (CCD)

32. Carbonate Compensation Depth New Deep Waters have low CO 2 conc. Old Deep Waters have high CO 2 conc. –Animal respiration –Decomposer activities Pacific Deep Waters are older than Atlantic Deep Waters

33. Global Thermohaline Circulation

34. Carbonate Compensation Depth & Greenhouse Effect? CO 2 atm, seawater & sediments are interrelated! Will increase in atmospheric CO 2 cause an increase in dissolved seawater CO 2 ? Consequences of a shallow CCD? Release into atmosphere of dissolved carbonate sediments?

35. Total dissolved inorganic carbon formation and decomposition of organic matter (1) from dissolution of Calcium Carbonate (2)

36. Carbonic Acid Bicarbonate Ion Carbon Dioxide and Carbonate system Carbonate

37. CO 2 changes in the last 50 yr Oceans Biosphere Rock Weathering

38. What controls the absorption of Carbon Dioxide in the ocean? How can we measure it? The carbonate system chemistry in seawater The concept of alkalinity, pH …

39. Alkalinity = ability of subtances to react with H + during titration of seawater with a strong acid. CO 3 = + H +  HCO 3 - HCO 3 - + H +  H 2 CO 3 B(OH) 4 - + H +  B(OH) 3 + H 2 O Titration Alkalinity = 2[CO 3 = ] + [HCO 3 - ] + [B(OH) 4 - ] + [OH-] - [H + ]

40. recall: Titration Alkalinity = 2[CO 3 = ] + [HCO 3 - ] + [B(OH) 4 - ] + [OH-] - [H + ] Carbonate Alkalinity (CA) = 2[CO 3 = ] + [HCO 3 - ] so CA -  CO 2 = CO 3 =

41. What happens if I add or remove CO2 by photosynthesis and respiration? It does not change Alkalinity. Photosynthesis CO 2 + H 2 O  CH 2 O + O 2 Respiration CH 2 O + O 2  CO 2 + H 2 O

42. What happens if dissolve or precipitate calcium carbonate? It does change Alkalinity. CaCO 3  Ca 2+ + CO 3 =

43. Total dissolved inorganic carbon from dissolution of Calcium Carbonate (2) +alkalinity -alkalinity Total dissolved inorganic carbon

45. What happens if I add or remove CO2 by photosynthesis and respiration? Does not change Alkalinity Photosynthesis CO 2 + H 2 O  CH 2 O + O 2 Respiration CH 2 O + O 2  CO 2 + H 2 O Titration Alkalinity = 2[CO 3 = ] + [HCO 3 - ] + [B(OH) 4 - ] + [OH-] - [H + ]

46. CO 2 O2O2 pH acidbasic

48. Carbon Cycle