The Carbon Cycle: Global to local Ruth Varner, PhD

1. The Carbon Cycle: Global to local Ruth Varner, PhD

2. Atmospheric CO2 at Mauna Loa Keeling, C.D. and T.P. Whorf. 2004. Atmospheric CO2 records from sites in the SIO air sampling network. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.

3. The Earth System • The Earth is a system made up of components. • There are feedbacks between these components. • These relationships can be used to predict past and future changes in the environment. • The Carbon cycle is an important Earth System.

5. Formation of Fossil Carbon • Coal: from the remains of plants (mainly from Carboniferous period) • Oil: from marine organisms that were buried under ocean or river sediments • Natural Gas: was originally oil; higher temperature and pressure converted it to primarily methane

7. Combustion Burning hydrocarbons produces CO2 and CO: CxHx + O2CO2 + H2O (if enough O2) Complete combustion  Hydrocarbon + oxygen = carbon dioxide and water CxHx + O2CO2 + CO + H2O (if not enough O2) incomplete combustion  Hydrocarbon + oxygen = carbon dioxide and carbon monoxide and water

9. Biological uptake/release of CO2 Photosynthesis – carbon fixed from inorganic CO2 to organic molecules (sugars) 6 CO2 + 6 H2O C6H12O6 + 6 O2 chlorophyll, sunlight Respiration – sugar is “burned” as part of a metabolic process that consumes oxygen and produces energy (ATP) – decomposition results in respiration C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

10. From the Atmosphere: Inorganic C in the Ocean CO2 (atm) ↔ CO2 (aq) ↔ HCO3- + H+ ↔ CO32- + H+↔ CaCO3 ↔ seds

11. Carbon dioxide in the oceans Calcareous skeleton carbon– can be dissolved or deposited

13. UNH/NOAA-PMEL CO2 Buoy in Gulf of Maine In overlying atmosphere In sea water

18. Terrestrial Carbon • Soil carbon is released through respiration : root and microbial (decomposition) • Plants respire CO2 • Plants also fix carbon through photosynthesis

19. Terrestrial Carbon Biological uptake/release of CO2 Photosynthesis – carbon fixed from inorganic CO2 to organic molecules (sugars) 6 CO2 + 6 H2O C6H12O6 + 6 O2 chlorophyll, sunlight Respiration – sugar is “burned” as part of a metabolic process that consumes oxygen and produces energy– decomposition results in respiration C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

20. FLUXNET • Global network of flux towers used to measure CO2 exchange between ecosystems and the atmosphere • Sites also include measurements on vegetation, soils, hydrology and meteorology. • Information available to researchers, students and educators.

21. http://www.fluxnet.ornl.gov/fluxnet/index.cfm

22. Total ecosystem respiration =Rsoil + Rleaf + Rstem + Rcwd Rleaf Rstem Rcwd Rsoil

23. Rsoil = Rroot + Rdecomp Soil CO2 efflux is a measurement of the Rsoil that reaches the atmosphere

24. Measuring Soil CO2 Efflux Manual chamber measurements Autochamber measurements

25. Volcanic CO2 Subduction of limestone at plate boundaries Carbonotype: watery low temperature lava

26. Oceans +2 Pg yr-1 Atmosphere +2 Pg yr-1

27. Carbon Fertilization ? FACE Duke Forest, Chapel Hill, NC

28. FACE site locations

29. Carbon cycling in temperate ecosystems

32. c9 c5 c6 c10 c7 c11 c8 c1 c2 c4 c3 • Temperate poor fen in southeastern New Hampshire (43 12.5’N, 71 3.5’W) • Area: 1.7 ha • Peat depth: 2-4.5m • Mean annual precipitation: 1100 mm • Mean annual temperature: 8.1 C • Mean growing season T: 14.9 C • Biologically active season from April-October • Sphagnum dominated • Other important species are leatherleaf, blueberry, sedge

33. Automated ChamberFluxes Control System Box Pump Select to chamber MFC IRGA LI6262 Select from chamber Clear Lexan Boxes 0.07 – 0.08 m3 (5) 0.14 – 0.16 m3 (5) Distributed Return Manifold Fans mix headspace A flux every 20 minutes 96 fluxes per day

34. Manual ChamberFluxes • CH4: Grab samples taken during chamber measurements; analyzed on an GC-FID • CO2: IRGA (LiCor 6200) analyzes air from chamber headspace; calculates NEE

35. 1995 2007 Vegetation survey maps of Sallie’s Fen from 1995 and 2007.

36. Research Questions?