1. Earth System History GEOL 1020 [15] Announcements More about global geochemical cycles September 30, 2013

2. About plants and carbon fixation….

4. The photosynthesis-respiration cycle in plants. THIS DIFFERENCE IN BEHAVIOR OF THE BOND STRENGTHS, CAN BE TRACED USING CARBON ISOTOPES!! KNOW THIS BIOLOGICAL SYSTEMS PREFER THE LIGHT ISOTOPE OF CARBON ( 12 C) OVER THE HEAVY ISOTOPE ( 13 C).

5. What is the relationship between burial of plant debris and atmospheric chemistry? The CO 2 and O 2 system CO 2 DOWN  O 2 UP CO 2 UP  O 2 DOWN

6. Respiration “BURNS” organic matter back to CO 2

7. And consumes Oxygen in the process…

8. OXIDATION CO2 formation Rapid burial of organic matter cuts it off from oxygen, therefore no feedback to CO 2 !! KNOW THIS:

9. 13 C / 12 C ratio in atmosphere is steady here. 13 C / 12 C ratio in atmosphere is increasing here!

10. PREFERS CARBON-12 Carbon-12 enriched Organic matter gets Buried. Carbon-12 gets Depleted in atmosphere Case Study: Increased plant growth and/or increased carbon burial Oxygen starts to build up.

11. What is the relationship between burial of plant debris and atmospheric chemistry? The CO 2 and O 2 system CO 2 DOWN  O 2 UP CO 2 UP  O 2 DOWN

13. Time (samples from bottom to top) Amount of CO 2 in atmosphere Case Study: Decreased plant growth and/or decreased carbon burial TEMPERATURE?? IS IT GETTING HOTTER OR COLDER WITH TIME? A. COLDER B. HOTTER

14. time CO 2 in atmosphere Case Study: Decreased plant growth and/or decreased carbon burial TEMPERATURE!! IS IT GETTING HOTTER OR COLDER OUTSIDE? A. COLDER B. HOTTER BECAUSE CO2 IS A GREENHOUSE GAS, IT TRAPS WARMTH AND WARMS THE AIR

15. time OXYGEN LEVELS? time 13 C/ 12 C In atmosphere & sediments Case Study: Decreased plant growth and/or decreased carbon burial OXYGEN LEVELS? A. B. C.

16. time OXYGEN LEVELS? time 13 C/ 12 C In atmosphere & sediments Case Study: Decreased plant growth and/or decreased carbon burial OXYGEN LEVELS? C.

17. OXIDATION CO2 formation Returns Carbon-12 to atmosphere Rapid burial of organic matter cuts it off from oxygen, therefore no feedback to CO 2 !! KNOW THIS:

18. 13 C / 12 C ratio in atmosphere is steady here. 13 C / 12 C ratio in atmosphere is increasing here!

19. Mid-Cretaceous

20. RECALL: if CO 2 goes down, O 2 goes up if O 2 goes down, CO 2 goes up More organic carbon burial = left-over HEAVY carbon in atmospheric CO 2. With increasing burial of organic matter, or increasing FLUX (input) into sedimentary reservoir, CO 2 level goes DOWN

21. 13 C / 12 C ratio in atmosphere is steady. 13 C / 12 C ratio in atmosphere is increasing! 13 C/ 12 C ratio changes over time COLD WARM

22. In the marine system, the same relationship between increased burial of organic matter in INCREASE in the stable carbon isotope ratio ( 13 C/ 12 C) holds!