by Dr. Xiaoming Zu, UPR Rio Piedras 2010

1. Carbon Cycles Xiaoming Zou Institute for Tropical Ecosystem Studies, University of Puerto Rico

3. Global environmental changes

4. Natural rhythms and disturbances

5. Climate

6. Geological events

7. Anthropogenic influence

8. Land use

9. Fossil fuel combustion

12. Ocean Structure and Properties Ocean circulation Surface water Well mixed Warm water Little change in temperature Movement caused by wind Earth rotation drives surface current from east to west along the equator Mean residence time 1700 years

13. Ocean Structure and Properties Ocean circulation Deep water Stratified Cold water with an average temperature of 3 C Sharp decrease in temperature in the thermocline, stable temperature further deeper Movement caused by water density and salinity Mean residence time 34000 years

14. Carbon Distribution in Ocean

17. Structure and Properties of the Atmosphere Structure and physical properties Troposphere (0-10 km) Stratosphere (10-50 km) Temperature Pressure (log P = - 0.06 A) Density

20. Global circulation Occurs in troposphere Upward near equator and at 60 degrees of latitude Downward at 30 and 90 degrees of latitude Structure and Properties of the Atmosphere

21. Carbon Distribution in Atmosphere

22. Atmospheric CO2 was much higher 390 M yrs ago than now

23. Lignin was evolved first in ferns 390 M yrs ago With lignin, plants could grow much taller and root deeply

24. Lignin decomposers were evolved at least 50 M yrs later Most coal formed during this mismatch between lignin producers and decomposers.

25. Before combustion of fossil fuel for more than 650 thousand years, atmospheric CO2 has fluctuated between180 and 300 parts per million.

26. Now things are changing again,mostly from the burning of fossil fuels.

27. Structure and Properties of Land

30. Carbon Distribution on Land Light Altitude Latitude Aspects Water Nutrients

32. Carbon Distribution on Land

34. Global Carbon Cycle Pools Atmosphere 750 x 10^15 g Ocean water 38,000 x 10^15 g Plant biomass 560 x 10^15 g Soil organic matter and soil biomass 1,500 x 10^15 g Total active pool: 40,000 x 10^15 Organic sediments 1.56 x 10^22 g Inorganic sediments 6.5 x 10^22 g

35. Global Carbon Cycle Fluxes Terrestrial GPP 120 x 10^15 g/y Ocean GPP 92 x 10^15 g/y Terrestrial Rp 60 x 10^15 g/y Terrestrial Rd 60 x 10^15 g/y Deforestation 0.9 x 10^15 g/y Anthropogenic 6 x 10^15 g/y Ocean R 90 x 10^15 g/y River flow 0.8 x 10^15 g/y

36. Global Carbon Cycle Residence time Atmosphere: 750/152 = 4.9 years Plant biomass: 560/60 = 9.3 years Soil organic C: 1500/60 = 25 years Surface ocean: 1020/90 = 11.3 years Entire ocean: 3800/90 = 422

37. Mechanisms for Carbon Stabilization and Destabilization Reduction in decomposition of organic carbon Litter quality with high lignin content Land management (reduced earthworms, reduced O2 levels, increased N input, etc) Reduction in deforestation and combustion of fossil fuel Increase in primary productivity Iron fertilization in ocean Chemical fertilizers in land N2 fixation Increase inorganic carbon pool Increase ocean water pH Reduced acid rain

39. Greenhouse Effect 1951-1997 Carbon dioxide (70%), nitrous oxide, methane (23%), ozone, chlorofluorocarbons (CFCs), and water vapor A molecule of methane is 21 times more potent than a molecule of carbon dioxide as a heat-trapping gas Vegetation has migrated since postglacial warming, but has failed to keep pace with changing climate because the greenhouse effect waarms 50-100 times faster than postglacial warming

40. “Double loop" model of SOM dynamics CO2 Non-lignin decomposers Geochemical processes Non-lignin decomposers Lignolytic Microbes Physical Protection Slow C Active C Passive C Labile C decomposing Microbes Chemical bonding Lignolytic Microbes Microbial C Geochemical processes LOC/N control

41. Global Environmental ChangesNatural rhythms

42. Global Environmental ChangesHuman Activities 1980 1994